This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colon Cancer focuses on systemic therapy options for the treatment of metastatic colorectal cancer (mCRC), because important updates have recently been made to this section. These updates include recommendations for first-line use of checkpoint inhibitors for mCRC, that is deficient mismatch repair/microsatellite instability-high, recommendations related to the use of biosimilars, and expanded recommendations for biomarker testing. The systemic therapy recommendations now include targeted therapy options for patients with mCRC that is HER2-amplified, or BRAF V600E mutation–positive. Treatment and management of nonmetastatic or resectable/ablatable metastatic disease are discussed in the complete version of the NCCN Guidelines for Colon Cancer available at NCCN.org. Additional topics covered in the complete version include risk assessment, staging, pathology, posttreatment surveillance, and survivorship.

The NCCN Guidelines for Rectal Cancer provide recommendations for the diagnosis, evaluation, treatment, and follow-up of patients with rectal cancer. These NCCN Guidelines Insights summarize the panel discussion behind recent important updates to the guidelines. These updates include clarifying the definition of rectum and differentiating the rectum from the sigmoid colon; the total neoadjuvant therapy approach for localized rectal cancer; and biomarker-targeted therapy for metastatic colorectal cancer, with a focus on new treatment options for patients with BRAF V600E– or HER2 amplification–positive disease.

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Germline mutations in CDKN2A have been reported in pancreatic cancer families, but genetic counseling for pancreatic cancer risk has been limited by lack of information on CDKN2A mutation carriers outside of selected pancreatic or melanoma kindreds. Lymphocyte DNA from consecutive, unselected white non-Hispanic patients with pancreatic adenocarcinoma was used to sequence CDKN2A. Frequencies of mutations that alter the coding of p16INK4 or p14ARF were quantified overall and in subgroups. Penetrance and likelihood of carrying mutations by family history were estimated. Among 1537 cases, 9 (0.6%) carried germline mutations in CDKN2A, including three previously unreported mutations. CDKN2A mutation carriers were more likely to have a family history of pancreatic cancer (P¼0.003) or melanoma (P¼0.03), and a personal history of melanoma (P¼0.01). Among cases who reported having a first-degree relative with pancreatic cancer or melanoma, the carrier proportions were 3.3 and 5.3%, respectively. Penetrance for mutation carriers by age 80 was calculated to be 58% for pancreatic cancer (95% confidence interval (CI) 8-86%), and 39% for melanoma (95% CI 0-80). Among cases who ever smoked cigarettes, the risk for pancreatic cancer was higher for carriers compared with non-carriers (HR 25.8, P¼2.1Â10 À13 ), but among nonsmokers, this comparison did not reach statistical significance. Germline mutations in CDKN2A among unselected pancreatic cancer patients are uncommon, although notably penetrant, especially among smokers. Carriers of germline mutations of CDKN2A should be counseled to avoid tobacco use to decrease risk of pancreatic cancer in addition to taking measures to decrease melanoma risk. Keywords: cyclin-dependent kinase inhibitor p16; genes; p16; pancreatic neoplasms INTRODUCTION Pancreatic cancer is associated with very poor survival rates, with long-term survivors limited to those with resected early stage tumors. However, detection of pancreatic cancer at an early stage is challenging, and this mandates identification of high-risk groups to be targeted for prevention and screening intervention.Since first observed by Lynch and Krush in 1968, 1 the incidence of pancreatic cancer has been noted to be increased in many families affected by inherited melanoma syndromes. In genetic analyses of these families, 20-40% of inherited increased melanoma susceptibility can be linked to mutations of the CDKN2A gene (p16/Ink4) located on chromosome 9p21. [2][3][4][5] As a result of the increased incidence of pancreatic cancer in melanoma families with CDKN2A mutations, it was hypothesized that mutations likely also predispose to pancreatic cancer development. 2 Mutations in CDKN2A have subsequently been described in familial pancreatic cancer kindreds, some without melanoma. 3,4 Somatic mutations of CDKN2A are present in up to 95% of pancreatic tumors. 5 These findings provide further support for the premise that CDKN2A mutations have an important role in the development of pancreatic cancer. Clinical findings in mutation carri...

Small bowel adenocarcinoma (SBA) is a rare malignancy of the gastrointestinal tract that has increased in incidence across recent years. Often diagnosed at an advanced stage, outcomes for SBA are worse on average than for other related malignancies, including colorectal cancer. Due to the rarity of this disease, few studies have been done to direct optimal treatment, although recent data have shown that SBA responds to treatment differently than colorectal cancer, necessitating a separate approach to treatment. The NCCN Guidelines for Small Bowel Adenocarcinoma were created to establish an evidence-based standard of care for patients with SBA. These guidelines provide recommendations on the workup of suspected SBA, primary treatment options, adjuvant treatment, surveillance, and systemic therapy for metastatic disease. Additionally, principles of imaging and endoscopy, pathologic review, surgery, radiation therapy, and survivorship are described.

This selection from the NCCN Guidelines for Rectal Cancer focuses on management of malignant polyps and resectable nonmetastatic rectal cancer because important updates have been made to these guidelines. These recent updates include redrawing the algorithms for stage II and III disease to reflect new data supporting the increasingly prominent role of total neoadjuvant therapy, expanded recommendations for short-course radiation therapy techniques, and new recommendations for a “watch-and-wait” nonoperative management technique for patients with cancer that shows a complete response to neoadjuvant therapy. The complete version of the NCCN Guidelines for Rectal Cancer, available online at NCCN.org, covers additional topics including risk assessment, pathology and staging, management of metastatic disease, posttreatment surveillance, treatment of recurrent disease, and survivorship.

Small bowel adenocarcinoma (SBA) is a rare cancer that has been treated similarly to colorectal cancer (CRC) in the advanced setting. Incidence has been increasing as detection efforts have been improving for these challenging-to-diagnose tumors, but patients frequently experience prolonged nonspecific symptoms due to delayed diagnosis. As a result of such delays and likely due to variant biology, patient outcomes for SBA are inferior to those for CRC at all stages of diagnosis. Recent molecular studies highlight the genomic differences underpinning these tumors and suggest new future pathways for treatment, distinct from CRC.