Neoadjuvant treatment of breast cancer: implications for the pathologist

These past few years, neoadjuvant strategy has taken an increasing place in the management of breast cancer patients. This strategy is mainly indicated to obtain a tumour bulk regression allowing a breast conserving surgery in patients that otherwise would have undergone mastectomy. Of note, development of new chemotherapy agents and targeted therapies has critically helped in the progress of neoadjuvant strategy as it is currently associated with better pathological response rates. In this context, the pathologist is at the crossroad of this multidisciplinary process. First, he provides on the initial core needle biopsy the tumour pathological characteristics that are critical for the choice of treatment strategy, i.e. histological type, histological grade, proliferative activity (mitotic count and Ki67/MIB1 index labeling), hormone receptor status (oestrogen receptor and progesterone receptor) and HER2 status. Secondly, the pathologist evaluates the pathological response and the status of surgical margins with regards to the residual tumour on the surgical specimen after neoadjuvant treatment. These parameters are important for the management of the patient, since it has been shown that complete pathological response is associated with improved disease free survival. Several grading systems are used to assess the pathological response in breast and axillary lymph nodes. The most frequently used in France are currently the systems described by Sataloff et al. and Chevallier et al. In this review, we detail the different steps involving the pathologist in neoadjuvant setting, with special regards to the quality process and future perspectives such as emerging predictive biomarkers.     

Integrins in breast cancer dormancy

Among breast cancer patients, 20% to 45% develop malignant lesions following their initial treatment. This relapse may occur after an apparent remission period that can range from years to several decades. Clinical observations suggest that breast-derived malignant cells have the ability to survive subclinically for a very long period of time before eventually resuming proliferation and forming detectable lesions. While the precise molecular events that correspond to this dormant phenotype remain poorly understood, data published during the last 10 years have underlined an important role of integrin proteins in the regulation of this phenomenon.     

Tumor initiating cells in malignant gliomas: biology and implications for therapy

A rare subpopulation of cells within malignant gliomas, which shares canonical properties with neural stem cells (NSCs), may be integral to glial tumor development and perpetuation. These cells, also known as tumor initiating cells (TICs), have the ability to self-renew, develop into any cell in the overall tumor population (multipotency), and proliferate. A defining property of TICs is their ability to initiate new tumors in immunocompromised mice with high efficiency. Mounting evidence suggests that TICs originate from the transformation of NSCs and their progenitors. New findings show that TICs may be more resistant to chemotherapy and radiation than the bulk of tumor cells, thereby permitting recurrent tumor formation and accounting for the failure of conventional therapies. The development of new therapeutic strategies selectively targeting TICs while sparing NSCs may provide for more effective treatment of malignant gliomas.     

Tumor dormancy and immunoescape

The role of the immune system in tumor dormancy is now well established. In several experimental models it is possible to induce tumor dormancy in immunocompetent hosts by prior immunization against tumor cells. Equilibrium between immune response and tumor cells leads to long-term tumor dormancy. This equilibrium is also observed early in tumor development and adaptive immunity may help contain tumor outgrowth. However, after variable times, tumor dormancy ends and the disease progresses. As the immune response remains active the tumor cells presumably escape dormancy by becoming resistant. Due to the extreme difficulty of isolating dormant tumor cells from patients, such mechanisms are poorly understood. However, experimental models have shown that dormant tumor cells may overexpress B7-H1 and B7.1, and inhibit CTL-mediated lysis. These cells resist apoptosis by methylating SOCS1, and by paracrine production of cytokines. The presence of immunoescape mechanisms in tumor cells from relapsing patients also suggests that the immune equilibrium which maintained dormancy has broken down. Identification of such mechanisms would offer new leads to favor the immune balance, and thus to clear minimal residual disease from patients.     

乳腺癌休眠动物模型的建立

目的模拟乳腺癌患者术后体内有少量肿瘤细胞存在,但长期无症状,也无特殊体征的特点而建立小鼠乳腺癌休眠模型并确定休眠细胞的存在。方法采用500个小鼠乳腺癌Ca761-03细胞肌肉接种于30只615小鼠,以小鼠2个月（相当人5年）不成瘤为休眠标准,按休眠观察组、休眠验证组和复发验证组三组（各10只小鼠）连续观察肿瘤休眠发生情况。肿瘤细胞休眠的确认方法为,采用给予连续外伤刺激,接种部位取材,组织固定和HE染色观察肿瘤再生成情况。结果500个小鼠乳腺癌Ca761-03细胞肌肉接种于小鼠2个月后,有30％小鼠成瘤,70％处于休眠状态。休眠肿瘤给予连续外伤刺激5个月后,有90％小鼠成瘤。显示乳腺癌肿瘤细胞可以在小鼠体内长期保持休眠状态,在外伤刺激的作用下,休眠的肿瘤细胞可以再次增殖,成为肿瘤复发的根源。结论成功建立了小鼠乳腺癌休眠模型,并用外伤刺激休眠细胞增殖的方法确定了休眠肿瘤细胞在体内的存在。这一动物模型填补了实体瘤休眠动物模型缺乏的空白。     

Tumor dormancy and oncogene addiction

Cancer is caused by genetic changes that activate oncogenes or inactivate tumor suppressor genes. The repair or inactivation of mutant genes may be effective in the treatment of cancer. Indeed, drugs that target oncogenes can be effective in the treatment of cancer. However, it is still unclear why the inactivation of a single cancer-associated gene would ever result in the elimination of tumor cells. In experimental transgenic mouse models the consequences of oncogene inactivation depend upon the genetic and cellular context. In some cases, oncogene inactivation results in the elimination of all or almost all tumor cells through apoptosis by the phenomenon described as oncogene addiction. In other cases, oncogene inactivation predominantly results in the terminal differentiation or cellular senescence of tumor cells. In yet others, oncogene inactivation results in the apparent loss of the neoplastic properties of tumor cells, which now appear and behave like normal cells; however, upon oncogene reactivation at least some of these cells rapidly recover their neoplastic phenotype. Thus, oncogene inactivation can result in a state of tumor dormancy. Hence, understanding when and how oncogene inactivation induces apoptosis, differentiation, and senescence within a tumor will be important when developing effective strategies for the treatment of cancer.     

Molecular biology of pancreatic cancer: potential clinical implications

The development of cancer involves the accumulation of genetic changes. Over the past decade there has a been spectacular advance in the knowledge of the genetic basis of cancer, mainly as a result of the rapid progression of molecular technology. Pancreatic cancer is one of the most lethal cancers. Conventional therapeutic approaches have not had much impact on the course of this aggressive neoplasm. Knowledge of the molecular biology of pancreatic cancer has grown rapidly. Genetic alterations in pancreatic cancer include oncogene mutations (most commonly K-ras mutations), and tumour suppressor gene alterations (mainly p53, pl6, DCC, etc.). These advances have potential implications for the management of this deadly disease. Identification of a hereditary genetic predisposition to pancreatic cancer has led to the formation of pancreatic cancer registries around the world, with voluntary screening of patients and siblings for the hereditary genetic defect. Asymptomatic population screening remains unrealistic, but the recognition of subpopulations at increased risk from pancreatic cancer, along with novel and sensitive detection techniques, means that targeted population screening is a step closer. Intensive research is performed in specialist laboratories to improve the diagnostic approach in patients with pancreatic cancer. The use of such molecular diagnostic methods is likely to expand. Molecular biology may also have a great impact on the treatment of pancreatic cancer, and many therapeutic approaches are being evaluated in clinical trials, including gene replacement therapy, genetic prodrug activation therapy, antisense immunology and peptide technology. The ‘molecular age’ has the promise of delivering still better results. This review summarises recent data relating to the molecular biology of pancreatic cancer, with emphasis on features that may be of clinical significance for diagnosis and/or therapy.     

Weddellite calcification in the breast: eighteen cases with implications for breast cancer screening

Breast tissue obtained from 18 of 246 women (7.3%) having localization biopsy for microcalcification contained crystals of Weddellite (calcium oxalate dihydrate). This was characterized by microscopic infra-red spectroscopy in three cases. Weddellite calcification was associated with benign lesions in 16 cases, but incidental atypical lobular hyperplasia and lobular carcinoma in situ were present, each in one case. Pathologists should be aware of this common non-haematoxyphilic, birefringent form of breast micro-calcification. Its presence has implications for the examination of biopsy specimens resulting from breast cancer screening using mammography.     

Proliferation in African breast cancer: biology and prognostication in nigerian breast cancer material.

Three hundred cases of invasive breast carcinoma from the University of Calabar Teaching Hospital, Nigeria were subjected to evaluation of proliferative activity by mitotic counts. The prognostic significance and association with other prognostic factors were evaluated. The mitotic activity was expressed as mitotic activity index (MAI), and standardized mitotic index (SMI). Pearson's correlation and univariate and multivariate Cox's regression were used. The mean follow-up time was 25.9 months. The mean values of SMI and MAI were 42.6 mitotic figures per square millimeter and 30.5 mitotic figures per 10 high-power fields, respectively, and these were much higher than values reported for Europe or other Western countries. The SMI had a positive correlation with tumor size (r = 0.31, P <.0001), histologic grade (r = 0.68, P <.0001), nuclear area (r = 0.45, P <.0001), and negative correlation with fraction of fields with tubular differentiation (FTD; r = -0.56, P = <0.0001). There was no statistically significant difference in the mitotic activity between the postmenopausal and the premenopausal patients. Also, lymph node-positive patients had higher counts than did lymph node-negative patients. Earlier determined grading associated decision thresholds divided the patients into groups of favorable and unfavorable prognosis. However, the statistically optimal thresholds for Nigerian material were different (32 and 92 mitotic figures per square millimeter for SMI). Tumor size of 5 cm, SMI, and MAI were independent prognostic factors. Nigerian breast cancers are high-grade, high-stage, and high-proliferating cancers occurring in a younger population than those of the Western countries. Proliferation is also more active. Evaluation of SMI or MAI can improve the distinction between aggressive and less aggressive variants of breast cancer.     

Diversity in cell surface sialic acid presentations: implications for biology and disease

Sialic acids (Sias) are typically found as terminal monosaccharides attached to cell surface glycoconjugates. They play many important roles in many physiological and pathological processes, including microbe binding that leads to infections, regulation of the immune response, the progression and spread of human malignancies and in certain aspects of human evolution. This review will provide some examples of these diverse roles of Sias and briefly address immunohistochemical approaches to their detection.     

Atypia in the assessment of breast cancer risk: implications for management

Proliferative disease accounts for as much as one-third of all biopsies for benign disease and 5-10% of proliferative lesions show atypia ductal or lobular hyperplasia. Nearly 40% of women with a family history of breast cancer and atypical hyperplasia subsequently develop breast cancer. A quantitative model developed by Gail and colleagues estimates the probability of developing breast cancer over time. Risk factors in the model include current age, ages at menarche and first live birth, number of previous biopsies, the presence of cellular atypia, and the number of first-degree relatives with breast cancer. Atypical hyperplasia approximately doubles the risk of developing invasive breast cancer within any quantitative risk profile. Ductal lavage provides a minimally invasive method of collecting breast epithelial cells. The procedure opens the possibility of repeatable tracking of breast cytology over time, but its role as a risk assessment tool remains to be fully defined.     

Tumor dormancy of primary and secondary cancers

Tumor dormancy is a phenomenon whereby cancer cells persist below the threshold of diagnostic detection for months to decades. This condition may arise due to either cell cycle arrest or a dynamic equilibrium state in which cell proliferation is in balance with cells undergoing apoptosis. Tumor dormancy is usually a reference to occult cancer cells that persist for an extended period of time after treatment, but primary cancers can also exhibit extended growth plateaus below the limits of detection. For example, autopsies of individuals who died of trauma reveal that most individuals harbor microscopic primary cancers. Mechanisms that operate independently or successively may restrict tumor expansion throughout tumor progression from incipiency to late-stage cancer. Proposed mechanisms include cell cycle withdrawal, immune surveillance, and blocked angiogenesis. The precise mechanisms underlying dormancy remain to be established, and relevant models will have an important impact on diagnostic and therapeutic strategies for treating cancer. This review summarizes the phenomenon of tumor dormancy, experimental models, and potential mechanisms.     

Genomic analysis of circulating cell-free DNA infers breast cancer dormancy

Biomarkers in breast cancer to monitor minimal residual disease have remained elusive. We hypothesized that genomic analysis of circulating free DNA (cfDNA) isolated from plasma may form the basis for a means of detecting and monitoring breast cancer. We profiled 251 genomes using Affymetrix SNP 6.0 arrays to determine copy number variations (CNVs) and loss of heterozygosity (LOH), comparing 138 cfDNA samples with matched primary tumor and normal leukocyte DNA in 65 breast cancer patients and eight healthy female controls. Concordance of SNP genotype calls in paired cfDNA and leukocyte DNA samples distinguished between breast cancer patients and healthy female controls (P < 0.0001) and between preoperative patients and patients on follow-up who had surgery and treatment (P = 0.0016). Principal component analyses of cfDNA SNP/copy number results also separated presurgical breast cancer patients from the healthy controls, suggesting specific CNVs in cfDNA have clinical significance. We identified focal high-level DNA amplification in paired tumor and cfDNA clustered in a number of chromosome arms, some of which harbor genes with oncogenic potential, including USP17L2 (DUB3), BRF1, MTA1, and JAG2. Remarkably, in 50 patients on follow-up, specific CNVs were detected in cfDNA, mirroring the primary tumor, up to 12 yr after diagnosis despite no other evidence of disease. These data demonstrate the potential of SNP/CNV analysis of cfDNA to distinguish between patients with breast cancer and healthy controls during routine follow-up. The genomic profiles of cfDNA infer dormancy/minimal residual disease in the majority of patients on follow-up.     

Tumor suppressors and cell metabolism: a recipe for cancer growth

Growing tumors face two major metabolic challenges—how to meet the bioenergetic and biosynthetic demands of increased cell proliferation, and how to survive environmental fluctuations in external nutrient and oxygen availability when tumor growth outpaces the delivery capabilities of the existing vasculature. Cancer cells display dramatically altered metabolic circuitry that appears to directly result from the oncogenic mutations selected during the tumorigenic process. An emerging theme in cancer biology is that many of the genes that can initiate tumorigenesis are intricately linked to metabolic regulation. In turn, it appears that a number of well-established tumor suppressors play critical roles in suppressing growth and/or proliferation when intracellular supplies of essential metabolites become reduced. In this review, we consider the potential role of tumor suppressors as metabolic regulators.     

Tumor markers in gynecological and breast cancer

Serum tumor markers are useful in diagnosis and follow-up for patients with gynecological malignancy or breast cancer. In epithelial ovarian cancer, CA125 has been identified as the most sensitive marker. Unfortunately, CA125 detection in the serum of patients with minimal malignant tumor has not been possible. Many nonmalignant conditions including endometriosis, menstruation and massive ascites may elevate the CA125, and almost 50% of patients with clear cell adenocarcinoma do not show CA125 elevated above 100 U/ml. To improve sensitivity and specificity in the diagnosis of ovarian cancer, the use of multiple tumor markers and the simultaneous use of image diagnosis should be employed. The value of tumor markers in the screening for cervical cancer and endometrial cancer has received little attention. However, the utility of serum SCC as a marker for monitoring cervical squamous cell carcinoma has been established. Since hCG is produced by gestational trophoblastic neoplasia and is a sensitive marker of trophoblastic cells in the body, patients with choriocarcinoma or invasive mole must be followed closely for this parameter. The improvement of the hCG detection technique has reduced the mortality rate from trophoblastic neoplasia. In breast cancer, many markers including CEA and CA15-3 are used, and they are reported to be useful as markers for monitoring.     

Isolation of functional single domain antibody by whole cell immunization: implications for cancer treatment

Carcinoembryonic antigen related cell adhesion molecule (CEACAM) 6 is over-expressed in different types of cancer cells. In addition, it has also been implicated in some infectious diseases. Targeting this molecule by an antibody might have applications in diverse tumor models. Single domain antibody (sdAb) is becoming very useful format in antibody engineering as potential tools for treating acute and chronic disease conditions such as cancer for both diagnostic as well as therapeutic application. Generally, sdAbs with good affinity are isolated from an immune library. Discovery of a new target antigen would require a new immunization with purified antigen which is not always easy. In this study, we have isolated, by phage display, an sdAb against CEACAM6 with an affinity of 5 nM from a llama immunized with cancer cells. The antibody has good biophysical properties, and it binds to the cells expressing the target antigen. Furthermore, it reduces cancer cells proliferation in vitro and shows an excellent tumor targeting in vivo. This sdAb could be useful in diagnosis as well as therapy of CEACAM6 expressing tumors. Finally, we envisage it would be feasible to isolate good sdAbs against other interesting tumor associated antigens from this library. Therefore, this immunization method could be a general strategy for isolating sdAbs against any surface antigen without immunizing the animal with the antigen of interest each time.