Curiethérapie du canal anal

Low dose-rate brachytherapy as a boost after concomitant chemoradiation therapy is a standard of care for locally advanced anal carcinoma, providing a rigorous selection taking into account the initial staging and tumor response to external beam radiotherapy. Local control is likely to be superior when the boost is performed with brachytherapy than with external beam radiotherapy. The several steps of the brachytherapy procedure are described. The standard treatment scheme is a concomitant chemoradiation therapy, including 45 Gy (1,8 Gy × 5) pelvic external beam radiotherapy and two courses of 5-fluorouracil and mitomycin-C, followed by a 15 Gy brachytherapy boost with a gap limited to 2 to 3 weeks. Higher irradiation dose for the most advanced cases has not yet demonstrated a therapeutic gain in terms of colostomy free survival. Exclusive brachytherapy for in-situ carcinoma or invasive carcinoma less than 10 mm is not recommended due to a high risk of local recurrence. Pulsed dose rate brachytherapy is an alternative to low dose rate brachytherapy (iridium wires) providing the respect of the recommended dose rate (0.5 to 1 Gy/hour). High dose rate brachytherapy is still under evaluation.     

Comparison between the ICRU rectal point and modern volumetric parameters in brachytherapy for locally advanced cervical cancer

PurposeThe implementation of image-guided brachytherapy in cervical cancer raises the problem of adapting the experience acquired with 2D brachytherapy to this technique. The GEC-ESTRO (Groupe européen de curiethérapie – European Society for Radiotherapy and Oncology) has recommended reporting the dose delivered to the rectum in the maximally exposed 2 cm³ volume, but so far, the recommended dose constraints still rely on 2D data. The aim of this study was to evaluate the relationship between the doses evaluated at the ICRU rectal point and modern dosimetric parameters.Material and methodsFor each patient, dosimetric parameters were generated prospectively at the time of dosimetry and were reported. For analysis, they were converted in 2 Gy equivalent doses using an α/β ratio of 3 with a half-time of repair of 1.5 hours.ResultsThe dosimetric data from 229 consecutive patients treated for locally advanced cervical cancer was analyzed. The mean dose calculated at ICRU point (DICRU) was 55.75 Gy ± 4.15, while it was 59.27 Gy ± 6.16 in the maximally exposed 2 cm³ of the rectum (P = 0.0003). The D2 cm³ was higher than the DICRU in 78% of the cases. The mean difference between D2 cm³ and DICRU was 3.53 Gy ± 4.91. This difference represented 5.41% ± 7.40 of the total dose delivered to the rectum (EBRT and BT), and 15.49% ± 24.30 of the dose delivered when considering brachytherapy alone. The two parameters were significantly correlated (P = 0.000001), and related by the equation: D2 cm³ = 0.902 × DICRU + 0.984. The r² coefficient was 0.369.ConclusionIn this large cohort of patients, the DICRU significantly underestimates the D2 cm³. This difference probably results from the optimization process itself, which consists in increasing dwell times above the ICRU point in the cervix. Considering these findings, caution must be taken while implementing image-guided brachytherapy and dose escalation.     

Clinical Impact of Computed Tomography-based Image-guided Brachytherapy for Cervix Cancer using the Tandem-ring Applicator — the Addenbrooke's Experience

AimsWe report our initial 3-year experience of chemoradiotherapy for cervical cancer with computed tomography-based image-guided high dose rate (HDR) brachytherapy using the tandem-ring applicator.Materials and methodsTwenty-eight patients were treated between February 2005 and December 2007. All patients received initial external beam radiotherapy (EBRT) followed by HDR brachytherapy (planned dose 21 Gy to point A in three fractions over 8 days). For each insertion, a computed tomography scan was obtained with the brachytherapy applicator in situ. The cervix, uterus and organs at risk (OAR) were contoured on the computed tomography images to create an individualised dosimetry plan. The D₉₀ (the dose delivered to 90% of the tumour target), V₁₀₀ (the percentage of tumour target volume receiving 100% of the prescribed dose) and the minimum dose in the most exposed 2 cm³ volume (D_2cc) of rectum, bladder and bowel were recorded. The equivalent dose in 2 Gy fractions delivered by EBRT and brachytherapy was calculated.ResultsThe 3-year cancer-specific survival was 81%, with a pelvic control rate of 96%. In 24 patients, a D₉₀ ≥74 Gy_α/β10 was achieved. The only patient with local recurrence had a D₉₀ of 63.8 Gy_α/β10. The overall actuarial risk of serious late morbidity was 14%. Seventeen patients had satisfactory OAR doses using the standard loading pattern. Seven patients had modifications to reduce the risk of toxicity, whereas two had modifications to improve the tumour dose. Comparison with a previous cohort of patients treated with chemoradiotherapy and a conventionally planned low dose rate triple source brachytherapy technique showed an improvement in local pelvic control of 20% (P = 0.04).ConclusionsThe implementation of a computed tomography-based tandem-ring HDR brachytherapy technique in conjunction with individual dose adaptation has resulted in a significant improvement in local control at Addenbrooke's without increasing the risk of serious toxicity, and with little effect on radiotherapy resources.     

Five-fraction HDR brachytherapy in locally advanced cervical cancer: A monocentric experience

PurposeThe 5-fraction scheme (5 × 5–5.5 Gy) is a common High-Dose Rate (HDR) intracavitary brachytherapy regimen for locally advanced cervical cancer (LACC). Yet, its equivalence with Pulse-Dose rate (PDR) schemes remains unproved. The present study aimed at reporting on the outcome of LACC patients treated with 5-fraction HDR brachytherapy.Materials and methodsThe medical records of all consecutive patients treated with curative-intent HDR brachytherapy for a LACC in a French Cancer Center were retrospectively reviewed.ResultsThirty-eight LACC patients underwent a 5-fraction intracavitary HDR brachytherapy between 2015 and 2019 (median dose = 25 Gy/5 fractions, following external-beam radiotherapy). Median age at diagnosis was 60 (range: 29–87). Thirty-one patients (81.5%) underwent concurrent chemotherapy. Tumor stages ranged from 3 IB2 (7.8%), 4 IB3 (10.5%), 4 IIA2 (10.5%), 12 IIB (31.7%), 1 IIIA (2.6%), 2 IIIB (5.3%), 7 IIIC1 (18.5%), 4 IIIC2 (10.5%), 1 IVA (2.6%) (2018 FIGO). Median D90% to CTV_HR reached 79.5 Gy (EQD2). Median D90% to CTV_IR reached 59.5 Gy (EQD2). Median Bladder D2cc was 69.8 Gy (EQD2). Median Rectum D2cc was 58.3 Gy (EQD2). Acute/late grade 3 toxicity was reported in one patient (2.6%). No grade 4–5 toxicity occurred. At a median 38 months follow-up, 10 patients (26.3%) had local (n = 7, 18.4%), nodal (n = 6, 15.7%) and/or distant (n = 7, 18.4%) relapse. Three-year overall survival rate was of 81.6%.ConclusionThe 5-fraction HDR scheme was well tolerated even in frail patients. Three-year local control was lower than expected. Treatment (absence of parametrial interstitial implants and use of cervical EBRT boost) and patients’ characteristics (age, comorbidities) may explain such results.     

Curiethérapie des cancers des voies aérodigestives supérieures

The main indications of brachytherapy for head and neck cancers are limited tumours of the oral cavity, the oropharynx and the nasopharynx. This technique can be exclusive, associated with external radiotherapy or postoperative. This is also a treatment for second localizations in previously irradiated areas. If low-dose rate brachytherapy is the reference, the pulse dose rate brachytherapy by control of the dose rate and optimisation of the dose distribution is the technique to be preferred. High-dose rate brachytherapy is an option. The major prognosis factors of local control and complications are the use of a leaded protection of the mandible, the intersource spacing (1.2–1.4 cm), the volume treated (30 cm³, i.e. three loops), the safety margin (5 mm), the dose rate (0.5 Gy/h), the total dose (65 Gy in case of exclusive brachytherapy, 25 Gy in case of a combination of external beam irradiation [50 Gy] and brachytherapy in the oropharyngeal carcinomas, 35 Gy in case of a combination of external beam irradiation [40 Gy] and brachytherapy in the oral cavity carcinomas, 60 Gy in case of a second localization in previous irradiated tissues), the delay between external irradiation and brachytherapy (< 20 days), the dose per fraction and the treated volume for high-dose rate brachytherapy. Brachytherapy, when possible, is the optimal method of irradiation of head and neck carcinomas with limited volume.     

Radiation dose to the low axilla in patients treated for early-stage breast cancer by locoregional intensity-modulated radiotherapy (IMRT)

PurposeTo determine the dose received by the low axilla during locoregional radiotherapy (RT) for early-stage breast cancer and to assess the impact of the treatment technique (three-dimensional conformal radiotherapy (3D-CRT) or rotational IMRT (VMAT) or helical tomotherapy (HT).Materials and methodsThe dosimetric study was performed on patients receiving normofractionated (NFRT - 50 Gy in 25 fractions) or hypofractionated (HFRT - 40 Gy in 15 fractions) locoregional radiotherapy (breast or chest wall and internal mammary, supraclavicular and infraclavicular nodes ± axillary nodes) by 3D-CRT or VMAT or HT at the Institut Curie Paris. Patients treated by breast-conserving surgery received a boost dose of 16 Gy and 10 Gy to the tumour bed, respectively.ResultsSixty-eight patients treated by RT from February 2017 to January 2019 were studied. The mean dose received by the low axilla when it was not part of the target volume was 30.8 Gy, 41.0 Gy and 44.4 Gy by 3D-CRT, VMAT and HT, respectively for NFRT and 24.2 Gy, 33.0 Gy and 34.9 Gy, respectively, for HFRT. With NFRT, 4.1% of the axilla received 95% (V95) of the prescribed dose by 3D-CRT compared to 24.5% and 33.6% by VMAT and HT, respectively; with HFRT, V95 was 3.9%, 19.5% and 24.1%, respectively.ConclusionThe axilla receives a non-negligible dose during locoregional radiotherapy; this dose is greater when VMAT or HT are used. Prospective studies must be conducted to assess the impact of this axillary dose in terms of morbidity, which currently remains unknown.     

Curiethérapie de haut débit de dose après radiothérapie externe d’un cancer de prostate : impact de la courbe d’apprentissage sur la dosimétrie

PurposeTo analyse the influence of the learning curve on dosimetric data for high-dose-rate brachytherapy prostate cancer boost.Patients and methodsFrom February 2009 to May 2012, after a first course of external beam radiation therapy (46 Gy/23 fractions), 124 patients underwent high-dose-rate brachytherapy boost using Plato™ (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden). The impact of the learning curve on the dosimetric quality of the prostate implant was assessed. The dosimetric data have been analysed: clinical target volume (CTV), D90 (dose to 90 % of CTV), D100, V100 (part on the CTV receiving 100 % of the dose), V150, V200 and DHI (dose non-homogeneity index). The doses delivered to 0.1, 1 and 2 cm³ of the rectum and urethra were calculated.ResultsDuring the study period (39 months), a significant reduction of V150 (P < 0.001), V200 (P < 0.001), D0.1rectum (P < 0.001), D1rectum (P < 0.001), D2rectum (P < 0.001), D0.1urethra (P < 0.001), and D1urethra (P < 0.002) was observed associated with a significant degradation of the D90 (P < 0.001) but not significant for the V100 (P = 0.29) and the D100 (P = 0.3).ConclusionThis study confirms that the dosimetric quality of high-dose-rate brachytherapy prostate implant is significantly improved during the learning curve period.     

Intraluminal brachytherapy boost following external beam radiotherapy with concurrent chemotherapy of oesophagus carcinoma: Results of a prospective observational study

Purpose

The main objective of our study is to evaluate response and toxicity profile in patients receiving external beam radiotherapy with concurrent chemotherapy followed by intraluminal brachytherapy boost for a carcinoma of the oesophagus.

Cancer du sein traité exclusivement par l’association d’une irradiation externe et d’une curiethérapie exclusive : résultats à long terme

PurposeTo report retrospective long-term results of historical experience of breast radiotherapy (RT) including external beam radiotherapy (EBRT) followed by low dose rate (LDR) brachytherapy.Patients and methodsBetween 1971 and 1983, at our service 474 breast cancer patients underwent exclusive conserving radiotherapy treatment. The RT included an initial external irradiation followed by interstitial LDR brachytherapy (37 Gy) to the residual tumour. The local regional nodes received 47.5 Gy followed by a 15 Gy boost delivered to the mammary nodes internal (IMN) and 25 Gy axilla.ResultsMedian follow-up was 139 months (8–342). There were 40 T1, 356 T2, and 78 T3. Local recurrences (LR) were observed in 20% of cases. The rate of recurrences free at 5, 10, 15 and 20 years were 86%, 77%, 73% and 67% respectively. At 5, 10, 15 and 20-year, the disease-free survival rates were 63%, 42%, 32% and 24%. Overall survival rates at 5, 10, 15 and 20-years were 75%, 53%, 34% and 25% respectively.ConclusionAlthough the historical retrospective character of these series, it is interesting to have this experience and to analyse it according to our new knowledge and advances. The described technique was a standard for many years and could be still used in some cases.     

Hypofractionated stereotactic radiotherapy for challenging brain metastases using 36 Gy in six fractions

PurposeStereotactic radiosurgery and hypofractionated stereotactic radiotherapy are standard treatments for brain metastases when they are small in size (at the most 3 cm in diameter) and limited in number, in patients with controlled extracerebral disease and a good performance status. Large inoperable brain metastases usually undergo hypofractionated stereotactic radiotherapy while haemorrhagic brain metastases have often been contraindicated for both stereotactic radiosurgery or hypofractionated stereotactic radiotherapy. The objective of this retrospective study was to assess a six 6 Gy-fractions hypofractionated stereotactic radiotherapy scheme in use at our institution for haemorrhagic brain metastases, large brain metastases (size greater than 15 cm³) or brain metastases located next to critical structures.Material and methodsPatients with brain metastases treated with the 6 × 6 Gy scheme since 2012 to 2016 were included. Haemorrhagic brain metastases were defined by usual criteria on CT scan and MRI. Efficacy, acute and late toxicity were evaluated.ResultsSixty-two patients presenting 92 brain metastases were included (32 haemorrhagic brain metastases). Median follow up was 10.1 months. One-year local control rate for haemorrhagic brain metastases, large brain metastases, or brain metastases next to critical structures were 90.7%, 73% and 86.7% respectively. Corresponding overall survival rates were 61.2%, 32% and 37.8%, respectively. Haemorrhagic complications occurred in 5.3% of patients (N = 5), including two cases of brain metastases with pretreatment haemorrhagic signal. Tolerance was good with only one grade 3 acute toxicity.ConclusionThe 6 × 6 Gy hypofractionated stereotactic radiotherapy scheme seems to yield quite good results in patients with haemorrhagic brain metastases, which must be confirmed in a prospective way.     

Cardiac substructures exposure in left-sided breast cancer radiotherapy: Is the mean heart dose a reliable predictor of cardiac toxicity?

PurposeThis study aimed to assess radiation dose distribution to cardiac subvolumes in left-sided breast cancer radiotherapy (LBCRT) and to clarify whether the mean heart dose (MHD) reliably reflects cardiac substructures exposure.Materials and methodsFifty women referred for adjuvant LBCRT were prospectively evaluated. All patients received 3D-conformal hypofractionated radiotherapy (40 Gy delivered in 15 fractions of 2.67 Gy ± boost of 13.35 Gy). Cardiac substructures were contoured using the F. Duane's cardiac atlas. Dose distribution to cardiac chambers, left main (LM), left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA)) was assessed. Dosimetric associations were analysed.ResultsThe mean MHD was 3.08 Gy (EQD2 = 3.67 Gy). The mean Dmean/Dmax LAD was 11.45 Gy (EQD2 = 13.64 Gy)/29.5 Gy (EQD2 = 35.15 Gy). Low doses were delivered to LM, LCx, and RCA (Dmean ≤ 1.3 Gy). The left ventricle (LV) was the most exposed cardiac chamber with Dmean/Dmax of 4.78 Gy/37 Gy. The strongest correlation with MHD was found for Dmean LAD (r = 0.81). For every 1 Gy increase in MHD, Dmean LAD rose by 3.4 Gy. However, the proportion of variance in Dmean LAD predictable from MHD was moderate (R² = 0.65). For all other cardiac substructures, R² values were < 0.7.ConclusionOur study showed high exposure of LAD and LV in LBCRT. With poor predictive value, MHD may underestimate doses to cardiac substructures. For optimal heart sparing radiotherapy, we recommend to consider LV and LAD as separate organ at risk.     

Comparison of dosimetric parameters and acute toxicity of intensity-modulated and three-dimensional radiotherapy in patients with cervix carcinoma: A randomized prospective study

PurposeThe use of intensity-modulated radiotherapy (IMRT) to treat cervix carcinoma has increased, however prospective randomized trials are still lacking.AimTo compare the dosimetric parameters and associated acute toxicity in patients with cervix carcinoma treated with three-dimensional (3D) conformal radiotherapy and IMRT.Patients and methodsForty patients were randomized in two arms each consisting of 20 patients. Patients in both arms received concurrent chemoradiation (cisplatin 40 mg/m² weekly; 50 Gy/25 fractions). Patients were treated with 3D conformal radiotherapy in one arm and with IMRT in another arm. After external beam radiotherapy, all patients received brachytherapy (21 Gy/3 fractions at weekly interval). For dosimetric comparison, both kinds of the plans were done for all the patients. All patients were assessed throughout and until 90 days after completion of treatment for acute gastrointestinal, genitourinary and hematologic toxicities.ResultsBoth plans achieved adequate planning target volume coverage, while mean conformity index was found significantly better in IMRT plans (P-value = 0.001). D₃₅ (dose to 35% volume) and D₅₀ for bladder was reduced by 14.62 and 32.57% and for rectum by 23.82 and 43.68% in IMRT. For IMRT, V₄₅ (volume receiving 45 Gy) of bowel were found significantly lesser (P-value = 0.0001), non-tumour integral dose was found significantly higher (P-value = 0.0240) and V₂₀ of bone marrow was found significantly reduced (P-value = 0.019) in comparison to that in 3D conformal radiotherapy. Significant reduction of grade 2 or more (20 vs 45%; P-value = 0.058) and grade ≥ 3 (5 vs 15%, P-value = 0.004) acute genitourinary toxicity and grade 2 or more (20 vs 45%, P-value = 0.003) and grade 3 or more (5 vs. 20%, P-value = 0.004) acute gastrointestinal toxicity while no significant difference for grade 2 and 3 or more haematological toxicity was noted in patients treated with IMRT compared to 3D conformal radiotherapy.ConclusionIMRT provide a good alternative for treatment of cervix carcinoma with lower acute gastrointestinal and acute genitourinary toxicity with similar target coverage compared to 3D conformal radiotherapy.     

Intensity-modulated Radiotherapy Allows Escalation of the Radiation Dose to the Pelvic Lymph Nodes in Patients with Locally Advanced Prostate Cancer: Preliminary Results of a Phase I Dose Escalation Study

AimPelvic irradiation in addition to prostate irradiation may improve outcome in locally advanced prostate cancer, but is associated with dose-limiting bowel toxicity. We report the preliminary results of a dose escalation study using intensity-modulated radiotherapy.Materials and methodsEligible patients had high-risk (T3, Gleason ≥8 or prostate-specific antigen ≥20 ng/ml) or lymph node-positive disease. Intensity-modulated radiotherapy was inverse planned giving 70 Gy/35 fractions to the prostate and 50 Gy/55 Gy/60 Gy in sequential cohorts to the pelvis with a 5 Gy boost to positive lymph nodes. Acute and late toxicity were recorded with Radiation Therapy Oncology Group (RTOG) and Late Effects Normal Tissue - Subjective Objective Management LENT-SOM scales. Neoadjuvant androgen suppression was given for 3 years. This report concerns the 50 and 55 Gy cohorts.ResultsSeventy-nine men were recruited (25 to 50 Gy/54 to 55 Gy) with a median follow-up of 2 years. Patients were divided into two groups according to the total bowel volume outlined (median 450 cm³). Acute RTOG (≥2) bowel toxicity was 40 and 50% for the 50 and 55 Gy groups and 38 and 51% for bowel volume <450 cm³ and ≥450 cm³, respectively, suggesting both volume and dose relationships for acute effects. Late RTOG diarrhoea ≥grade 2 was only seen with bowel volume ≥450 cm³, but no dose effect was apparent (12%/50 Gy and 10%/55 Gy). LENT-SOM bowel ≥grade 2 toxicity occurred in 22%/50 Gy and 15%/55 Gy. Only one patient had grade 3 toxicity. A dose volume histogram analysis showed increased late RTOG diarrhoea ≥grade 2 with larger bowel volume irradiated, significant for BV40 >124 cm³ (P = 0.04), BV45 >71 cm³ (P = 0.03) and BV60 >2 cm³ (P = 0.01).ConclusionsAcute and late bowel toxicity was acceptably low using a pelvic dose of up to 55 Gy over 7 weeks. Both relate to total pelvic bowel volume and dose volume constraints have been defined.     

High dose rate brachytherapy with customized applicators for malignant facial skin lesions

PurposeBrachytherapy is a well-known treatment in the management of skin tumors. For facial or scalp lesions, applicators have been developed to deliver non-invasive treatment. We present cases treated with customized applicators with high dose rate system.Material and methodsPatients with poor performance status treated for malignant skin lesions of the scalp or the facial skin between 2011 and 2014 were studied. Afterloading devices were chosen between Freiburg^® Flap, silicone-mold or wax applicators. The clinical target volume (CTV) was created by adding margins to lesions (10 mm to 20 mm). The dose schedules were 25 Gy in five fractions for postoperative lesions, 30 Gy in six fractions for exclusive treatments and a single session of 8 Gy could be considered for palliative treatments.ResultsIn 30 months, 11 patients received a treatment for a total of 12 lesions. The median age was 80 years. The median follow-up was 17 months and the 2-year local control rate was 91%. The mean CTV surface was 41.1 cm² with a mean thickness of 6.1 mm. We conceived three wax applicators, used our silicone-mold eight times and the Freiburg^® Flap one time. We observed only low-grade radiodermitis (grade I: 50%, grade II: 33%), and no high-grade skin toxicity.ConclusionHigh dose rate brachytherapy with customized applicators for facial skin and scalp lesions is efficient and safe. It is a good modality to treat complex lesions in patients unfit for invasive treatment.     

Feasibility evaluation of prone breast irradiation with the Sagittilt© system including residual-intrafractional error assessment

PurposeFeasibility evaluation of the Sagittilt^© prone breast board system (Orfit Industries, Wijnegem, Belgium) for radiotherapy focusing on patient and staff satisfaction, treatment time, treatment reproducibility with the assessment of residual-intrafractional errors.Material and methodsThirty-six patients underwent whole-breast irradiation in prone position. Seventeen received a sequential boost (breast: 42.56 Gy in 16 fractions, boost: 10 Gy in five fractions), while 19 patients received a concomitant boost protocol (breast/boost: 45.57/55.86 Gy in 21 fractions). Treatment verification included a daily online cone-beam CT (CBCT). In order to assess the residual and residual-intrafractional errors post-treatment CBCTs were performed systematically at the first five treatment sessions. Treatment time, patient comfort, staff satisfaction were also evaluated.ResultsThe pretreatment CBCT resulted in a population systematic error of 4.5/3.9/3.3 mm in lateral/longitudinal/vertical directions, while the random error was 5.4/3.8/2.8 mm. Without correction these would correspond to a clinical to planning target volume margin of 15.0/12.3/10.3 mm. The population systematic and random residual-intrafractional errors were 1.5/0.9/1.7 mm and 1.7/1.9/1.6 mm. Patient and staffs’ satisfaction were considered good and average. The mean treatment session time was 21 minutes (range: 13–40 min).ConclusionThe Sagittilt^© system seems to be feasible for breast irradiation and well-tolerated by patients, acceptable to radiographers and reasonable in terms of treatment times. Set-up accuracy was comparable with other prone systems; residual errors need further investigations.     

Doses dans les organes à risque en radiothérapie conformationnelle et en radiothérapie en conditions stéréotaxiques : la vessie

Bladder dose constraints in case of conformational radiotherapy/intensity-modulated radiotherapy and stereotactic radiotherapy are reported from the literature, in particular from the French radiotherapy society RECORAD recommendations, according to the treated pelvic tumor sites. The dose–volume effect on urinary toxicity is not clearly demonstrated, making difficult to establish absolute dose constraints for the bladder. In case of high-dose prostate cancer radiotherapy, the bladder dose constraints are: V60 Gy < 50% and maximum dose < 80 Gy for standard fractionation and V60 Gy < 5%, V48 Gy < 25% and  V41Gy < 50% for moderate hypofractionation (20 fractions of 3 Gy). In case of prostate stereotactic radiotherapy (five fractions of 7.25 Gy), the most frequent dose constraints in the literature are V37 Gy < 10 cm³ and V18 Gy < 40%. In case of conformational radiotherapy of cervix cancer, postoperative endometrium, anal canal and rectum, the recommendations are V40 Gy < 40% and D2% lower than the prescribed dose.     

Stereotactic radiotherapy for large solitary brain metastases

PurposeTo assess effectiveness and toxicity levels of stereotactic radiation therapy without whole brain radiation therapy in patients with solitary brain metastases larger than 3 cm.Patients and methodsBetween June 2007 and March 2009, 12 patients received fractionated stereotactic radiation therapy and 24 patients underwent stereotactic radiosurgery. For the fractionated stereotactic radiation therapy group, 3 × 7.7 Gy were delivered to the planning target volume (PTV); median volume and diameter were 29.4 cm³ and 4.4 cm, respectively. For the stereotactic radiosurgery group, 14 Gy were delivered to the PTV; median volume and diameter were 15.6 cm³ and 3.7 cm, respectively.ResultsMedian follow-up was 218 days. For the fractionated stereotactic radiation therapy group, local control rates were 100% at 360 days and 64% at 720 days; for the stereotactic radiosurgery group, rates were 58% at 360 days and 48% at 720 days (P = 0.06). Median survival time was 504 days for the fractionated stereotactic radiation therapy group and 164 days for the stereotactic radiosurgery group (P = 0.049). Two cases of grade 2 toxicity were observed in the fractionated stereotactic radiation therapy group, and 6 cases of grade 1–2 toxicity, in the stereotactic radiosurgery group.ConclusionsThis study provides data to support that fractionated stereotactic radiation therapy without whole brain radiation therapy with a margin dose of 3 fractions of 7.7 Gy for treatment of solitary large brain metastases is efficient and well-tolerated. Because of the significant improvement in overall survival, this schedule should be assessed in a randomized trial.     

Présentation de l’étude Gortec 2017-03 : radiothérapie en conditions stéréotaxiques postopératoire des cancers localisés de l’oropharynx et de la cavité buccale avec marges à risque (PHRC-K-16-164)

The GORTEC 2017-03-Stereo-postop study is a phase 2, multicentric, nationwide study, funded by the hospital clinical research program (PHRC). The sponsor is Centre Jean-Perrin in Clermont-Ferrand, in partnership with the GORTEC. The principal investigators are Dr J Biau and Dr M Lapeyre. The main objective is to study severe late toxicity of postoperative stereotactic radiotherapy (6 × 6 Gy) for early stage oropharyngeal and oral cavity cancer with high risk margins. The secondary objectives include acute toxicity, efficacy, nutritional impact and quality of life. The population is adult patients, with pT1 or pT2 squamous cell carcinoma of the oropharynx or oral cavity (except lips), without indication of neck irradiation or concomitant chemotherapy, with at risk margin (R1, less than 5 mm or uncertain). Ninety patients will be included over a 2-year period; this was calculated to limit the rate of 2-year severe toxicity at 5 to 15%, with a 2-year local control of at least 80 to 90%. If this study is considered as positive, stereotactic radiotherapy (6 × 6 Gy) could become the third therapeutic option, with brachytherapy and normofractionated intensity-modulated radiotherapy (IMRT), for postoperative irradiation of oropharyngeal and oral cavity cancer with high risk margins.     

Radionécrose après radiothérapie stéréotaxique d’une métastase cérébrale de 3 cm : la technique peut-elle améliorer les résultats dosimétriques ?

Stereotactic radiotherapy is a major issue in the management of brain metastases. Radionecrosis is a major concern, especially for large lesions. Optimizing dosimetric parameters is essential to allow optimal local control rate while minimizing potential toxicity. We report the case of a 30-mm brain metastases treated with stereotactic radiotherapy after initial whole brain radiotherapy, complicated with symptomatic radionecrosis. A dose of 24 Gy in three fractions on the 80% isodose were delivered using a dynamic conformal arc technique (Novalis TX^®). We realized a dosimetric comparison with: (i) optimization of initial conformal arc plan, (ii) volumetric modulated arctherapy with coplanar arcs and (iii) volumetric modulated arctherapy with coplanar and non-coplanar arcs. The optimal dose planning in terms of planning target volume coverage (99.2%) and normal brain sparing (V24 Gy = 0.4 cm³, V18 Gy = 6.5cm³, V10 Gy = 25.4 cm³, V5 = 83.9 cm³) was obtained with volumetric modulated arctherapy with coplanar and non-coplanar arcs. Volumetric modulated arctherapy-based stereotactic irradiation with coplanar and non-coplonar arcs seems an interesting option for the treatment of large brain metastases to optimize dosimetric parameters.