Prophylactic surgery in Lynch syndrome

Genetic Predisposition to Breast and Ovarian Cancers: How Many and Which Genes to Test?

Breast and ovarian cancers are some of the most common tumors in females, and the genetic predisposition is emerging as one of the key risk factors in the development of these two malignancies. BRCA1 and BRCA2 are the best-known genes associated with hereditary breast and ovarian cancer. However, recent advances in molecular techniques, Next-Generation Sequencing in particular, have led to the identification of many new genes involved in the predisposition to breast and/or ovarian cancer, with different penetrance estimates. TP53, PTEN, STK11, and CDH1 have been identified as high penetrance genes for the risk of breast/ovarian cancers. Besides them, PALB2, BRIP1, ATM, CHEK2, BARD1, NBN, NF1, RAD51C, RAD51D and mismatch repair genes have been recognized as moderate and low penetrance genes, along with other genes encoding proteins involved in the same pathways, possibly associated with breast/ovarian cancer risk. In this review, we summarize the past and more recent findings in the field of cancer predisposition genes, with insights into the role of the encoded proteins and the associated genetic disorders. Furthermore, we discuss the possible clinical utility of genetic testing in terms of prevention protocols and therapeutic approaches.

Advances in the study of Lynch syndrome in China

Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer, is an autosomal dominant genetic condition that has a high risk of colon cancer as well as other cancers due to inherited mutations in mismatch repair (MMR) genes. During the last decades, there have been great advances in research on Chinese Lynch syndrome. This review mainly focuses on the genetic basis, clinicopathologic features, diagnosis, intervention, chemoprevention, and surveillance of Lynch syndrome in China. In addition to frequently altered MMR genes, such as MLH1, MSH2, MSH6, and MLH3, other MMR-associated genes, such as those encoding human exonuclease 1, transforming growth factor β receptor 2, and alanine aminopeptidase, metastasis-associated protein 2, adenomatosis polyposis coli down-regulated 1, and hepatic and glial cell adhesion molecule have also been implicated in Chinese Lynch syndrome. Most Chinese researchers focused on the clinicopathologic features of Lynch syndrome, and it is noticeable that the most frequent extracolonic tumor in northeast China is lung cancer, which is different from other areas in China. The Chinese diagnostic criteria for Lynch syndrome have been established to identify gene mutation or methylation. With regard to chemoprevention, celecoxib may be effective to prevent polyps relapse in Lynch syndrome carriers. Additionally, a colonoscopy-based surveillance strategy for the prevention and early detection of neoplasms in Lynch-syndrome carriers has been proposed.

Prophylactic oophorectomy during primary colorectal cancer resection: A systematic review and meta-analysis

AIM: To appraise the current evidence for prophylactic oophorectomy in patients undergoing primary curative colorectal cancer resection.

METHODS: Occult ovarian metastases may lead to increased mortality, therefore prophylactic oophorectomy may be considered for women undergoing colorectal resection. A systematic review and meta-analysis was performed for English language studies from 1994 to 2014 (PROSPERO Registry number: CRD42014009340), comparing outcomes following prophylactic oophorectomy (no known ovarian or other metastatic disease at time of surgery) vs no ovarian surgery, synchronous with colorectal resection for malignancy. Outcomes assessed: local recurrence, 5-year mortality, immediate post-operative morbidity and mortality, and rate of distant metastases.

RESULTS: Final analysis included 4 studies from the United States, Europe and China, which included 627 patients (210 prophylactic oophorectomy and 417 non-oophorectomy). There was one randomized controlled trials, the remainder being non-randomised cohort studies. The studies were all at high risk of bias according to the Cochrane Collaboration’s assessment tool for randomised studies and the Newcastle-Ottawa Score for the cohort studies. The mean age of patients amongst the studies ranged from 56.5 to 67 years. There were no significant differences between the patients having prophylactic oophorectomy at time of primary colorectal resection compared with patients who did not with respect to local recurrence, 5-year survival and distant metastases. There was no difference in post-operative complications or immediate post-operative mortality between the groups.

CONCLUSION: Current evidence does not favour prophylactic oophorectomy for patients without known genetic predisposition. Prophylactic surgery is not associated with additional risk of post-operative complications or death.

The evolution of colorectal cancer genetics-Part 2: clinical implications and applications

The genetic understanding of colorectal cancer (CRC) continues to grow, and it is now estimated that 10% of the population has a known hereditary CRC syndrome. This article will examine the evolving surgical and medical management of hereditary CRC syndromes, and the impact of tumor genetics on therapy. This review will focus on the most common hereditary CRC-prone diseases seen in clinical practice, which include Lynch syndrome (LS), familial adenomatous polyposis (FAP) & attenuated FAP (AFAP), MutYH-associated polyposis (MAP), and serrated polyposis syndrome (SPS). Each section will review the current recommendations in the evaluation and treatment of these syndromes, as well as review surgical management and operative planning. A highly detailed multigeneration cancer family history with verified genealogy and pathology documentation whenever possible, coupled with germline mutation testing when indicated, is critically important to management decisions. Although caring for patients with these syndromes remains complex, the application of this knowledge facilitates better treatment of both individuals and their affected family members for generations to come.

Endoscopic and surgical management of hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome is a disease characterized by autosomal dominant clustering of colorectal cancer (CRC) as well as other cancers. It is critical for clinicians and surgeons caring for patients with HNPCC to be familiar with their management related to CRC. Based on retrospective studies, screening colonoscopy is recommended every 1 to 2 years beginning at age 20 to 25, or 10 years younger than the earliest CRC in the family (whichever is earlier). HNPCC patients with colon cancer should be considered for total abdominal colectomy rather than a more limited segmental colon resection due to the increased risk of metachronous neoplasia associated with the condition. Rectal cancer in HNPCC has not been well studied, but discussions with the patient regarding surgical management should weigh the risks of metachronous CRC with the morbidity and quality of life issues associated with proctocolectomy. Regardless of the procedure, a patient with HNPCC requires close postoperative endoscopic surveillance of any remaining at-risk mucosa. In terms of chemoprevention, aspirin has been shown to be effective in preventing colorectal neoplasia in prospective trials and should be considered in patients who do not have a contraindication to the drug. Trials for other chemopreventative agents in HNPCC are ongoing. As more is learned about particular genotype-phenotype correlations with Lynch syndrome, this will likely affect surgical decision making. Despite all of these efforts in the management of patients with HNPCC or Lynch syndrome, incident CRCs still occur, thus reinforcing the need for further studies to better understand the optimal management of these patients.