Controlled 15-year trial on screening for colorectal cancer in families with hereditary nonpolyposis colorectal cancer.
ABSTRACT Identification of the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome enables prevention of colorectal cancer (CRC) by means of colonoscopy and polypectomies. We evaluated the efficacy of screening in a controlled trial over 15 years.
Incidence of CRC and survival were compared in 2 cohorts of at-risk members of 22 families with HNPCC. Colonic screening at 3-year intervals was arranged for 133 subjects; 119 control subjects had no screening. Genetic testing was offered to subjects in whose families the causative mutation was known.
CRC developed in 8 screened subjects (6%) compared with 19 control subjects (16 %; P = 0.014). The CRC rate was reduced by 62%. In mutation-positive subjects alone, the CRC rates were 18% in screened subjects and 41% in controls (P = 0.02). The decrease resulted from the removal of adenomas in 13 mutation-positive individuals (30%) and in 6 subjects with unknown mutation status (40%). All CRCs in the study group were local, causing no deaths, compared with 9 deaths caused by CRC in the controls. The overall death rates were 10 vs. 26 subjects in the study and control groups (P = 0.003), 4 vs. 12 in mutation-positive subjects (P = 0.05).
Colonoscopic screening at 3-year intervals more than halves the risk of CRC, prevents CRC deaths, and decreases overall mortality by about 65% in HNPCC families.
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ABSTRACT: Carriers of a germline mutation in one of the DNA mismatch repair (MMR) genes have a high risk of developing numerous different cancers, predominantly colorectal cancer and endometrial cancer (known as Lynch syndrome). MMR gene mutation carriers develop tumors with MMR deficiency identified by tumor microsatellite instability or immunohistochemical loss of MMR protein expression. Tumor MMR deficiency is used to identify individuals most likely to carry an MMR gene mutation. However, MMR deficiency can also result from somatic inactivation, most commonly methylation of the MLH1 gene promoter. As tumor MMR testing of all incident colorectal and endometrial cancers (universal screening) is becoming increasingly adopted, a growing clinical problem is emerging for individuals who have tumors that show MMR deficiency who are subsequently found not to carry an MMR gene mutation after genetic testing using the current diagnostic approaches (Sanger sequencing and multiplex ligation-dependent probe amplification) and who also show no evidence of MLH1 methylation. The inability to determine the underlying cause of tumor MMR deficiency in these "Lynch-like" or "suspected Lynch syndrome" cases has significant implications on the clinical management of these individuals and their relatives. When the data from published studies are combined, 59% (95% confidence interval [CI]: 55% to 64%) of colorectal cancers and 52% (95% CI: 41% to 62%) of endometrial cancers with MMR deficiency were identified as suspected Lynch syndrome. Recent studies estimated that colorectal cancer risk for relatives of suspected Lynch syndrome cases is lower than for relatives of those with MMR gene mutations, but higher than for relatives of those with tumor MMR deficiency resulting from methylation of the MLH1 gene promoter. The cause of tumor MMR deficiency in suspected Lynch syndrome cases is likely due to either unidentified germline MMR gene mutations, somatic cell mosaicism, or biallelic somatic inactivation. Determining the underlying cause of tumor MMR deficiency in suspected Lynch syndrome cases is likely to reshape the current triaging schemes used to identify germline MMR gene mutations in cancer-affected individuals and their relatives.The Application of Clinical Genetics 01/2014; 7:183-93.
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ABSTRACT: To identify patients with endometrial cancer with potential Lynch-related DNA mismatch repair (MMR) protein expression defects and to explore the role of these defects in screening for LS.International journal of clinical and experimental pathology. 01/2014; 7(10):7297-303.
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ABSTRACT: This article explores the views of general practitioners and specialists on their referral of patients with suspected Lynch syndrome to cancer genetic services. Using a purposive maximum variation sampling strategy, we conducted semi-structured interviews face-to-face with 28 general practitioners and specialists in public or private hospitals and specialist clinics between March and August 2011. General practitioners and specialists were recruited in a major metropolitan area in Australia. Interview transcripts were reviewed by two independent researchers, and thematic analysis was performed using NVivo10 software. The main barriers and motivators identified were: (1) clinician-related (e.g., familiarity with Lynch syndrome and family history knowledge); (2) patient-related (e.g., patients' interests and personal experience with cancer); and (3) organizational-related (e.g., access to services, guidelines and referral pathway). Referral of patients with suspected Lynch syndrome to cancer genetic services is motivated and hindered by a range of individual, interpersonal and organizational factors. In order to improve the care and quality of life of patients and family with suspected Lynch syndrome, further research is needed to develop supportive tools for clinicians.Journal of personalized medicine. 03/2014; 4(1):20-34.