Prophylactic surgery to reduce the risk of gynecologic cancers in the Lynch syndrome.

BACKGROUND: Women with the Lynch syndrome (hereditary nonpolyposis colorectal cancer) have a 40 to 60 percent lifetime risk of endometrial cancer and a 10 to 12 percent lifetime risk of ovarian cancer. The benefit of prophylactic gynecologic surgery for women with this syndrome has been uncertain. We designed this study to determine the reduction in the risk of gynecologic cancers associated with prophylactic hysterectomy and bilateral salpingo-oophorectomy in women with the Lynch syndrome. METHODS: Three hundred fifteen women with documented germ-line mutations associated with the Lynch syndrome were identified. Women who had undergone prophylactic hysterectomy (61 women) and women who had undergone prophylactic bilateral salpingo-oophorectomy (47 women) were matched with mutation-positive women who had not undergone the procedure in question (210 women for the analysis of endometrial cancer and 223 for the analysis of ovarian cancer). Women who had undergone prophylactic surgery and their matched controls were followed from the date of the surgery until the occurrence of cancer or until the data were censored at the time of the last follow-up visit. RESULTS: There were no occurrences of endometrial, ovarian, or primary peritoneal cancer among the women who had undergone prophylactic surgery. Endometrial cancer was diagnosed in 69 women in the control group (33 percent), for an incidence density of 0.045 per woman-year, yielding a prevented fraction (the proportion of potential new cancers prevented) of 100 percent (95 percent confidence interval, 90 to 100 percent). Ovarian cancer was diagnosed in 12 women in the control group (5 percent), for an incidence density of 0.005 per woman-year, yielding a prevented fraction of 100 percent (95 percent confidence interval, -62 to 100 percent). CONCLUSIONS: These findings suggest that prophylactic hysterectomy with bilateral salpingo-oophorectomy is an effective strategy for preventing endometrial and ovarian cancer in women with the Lynch syndrome.

Tumor histology helps to identify Lynch syndrome among colorectal cancer patients.

OBJECTIVE: To determine the value of histology in identifying Lynch syndrome among those patients with early onset of colorectal cancer (CRC). METHODS: Demographic, clinical and cancer history data from patients diagnosed with CRC before 60 years of age, and treated at our institution between 1997 and 2005, were collected from medical records and direct interview. Their tumors were assessed to identify histological features suggestive of high frequency microsatellite instability (MSI-H): tumor infiltrating lymphocytes, Crohn's like inflammatory reaction, mucinous, signet ring cells, medullary growth pattern and then, tested for microsatellite instability (MSI) and MLH1/ MSH2 protein expression. RESULTS: Sixty-five patients were included in the study. The mean age at diagnosis was 48 +/- 9.9 years. Overall, 28 (43%) patients, including 13 of 35 diagnosed between ages 50 and 60, had tumor demonstrating one or more histological features suggestive of MSI-H. These patients were younger (45 vs. 50 years, P = 0.02) and more commonly had family history of Lynch syndrome-related cancers (36 vs. 19%), though the latter feature did not reach statistical significance (P = 0.07). Eleven of 25 tumors with MSI-H histology, but only 1 of 29 tumors without special histological features were found to be MSI-H (P < 0.0001). Histology had a positive predictive value of 44% and a negative predictive value of 97% for identifying MSI-H tumors. CONCLUSIONS: Limiting MSI analysis only to those tumors with suggestive histology would have reduced the need for testing by nearly 60% of all tumors from patients that met the revised Bethesda guidelines.

A comparison of the phenotype and genotype in adenomatous polyposis patients with and without a family history.

OBJECTIVES: Adenomatous polyposis of the colon is often secondary to an inherited mutation in adenomatous polyposis coli (APC) gene, however, approximately one third of patients have no family history of the disease. We studied the phenotype and genotype of adenomatous polyposis in patients without a family history. METHODS: A cohort of 57 unrelated adenomatous polyposis patients were evaluated. Seventeen patients with no family history were compared with 40 patients who had a positive family history of the disease. Family history and medical records were collected and analyzed. Germline APC and Mut Y homologue (MYH) testing was undertaken. RESULTS: Patients without a family history were diagnosed with polyposis at an older age (41 years vs. 32 years) and presenting more frequently with symptoms (76 vs 20, P < 0.05). The number of colonic polyps and frequency of extracolonic manifestation associated with adenomatous polyposis did not differ between the two groups. APC mutations were detected less frequently among patients without a family history of the disease (4 out of 17 vs 25 out of 40, P=0.007), even among those with greater than 100 colorectal adenomas (4 out of 12 versus 21 out of 29, P=0.03). One homozygous MYH mutation carrier (G382D) was detected among the six patients without a family history and without a germline APC mutation who were tested. CONCLUSIONS: Adenomatous polyposis patients without a family history are usually diagnosed with symptoms, and at a later age. Phenotypically, they are similar to those with a family history. However, germline APC mutations are detected far less frequently in patients without a family history. A small percentage of these cases may be secondary to biallelic germline MYH mutations.

Genotype and phenotype of patients with both familial adenomatous polyposis and thyroid carcinoma.

The incidence of thyroid carcinoma in familial adenomatous polyposis (FAP) is thought to be 1%-2%, with the majority of cases being female. We have investigated the phenotype and genotype of 16 patients with FAP associated thyroid carcinoma. Among 1194 FAP patients studied in two high risk registries in North America (Familial Gastrointestinal Cancer Registry, Toronto and University California, San Francisco), 16 (1.3%) unrelated patients with FAP associated thyroid cancers were identified. Adenomatous polyposis coli (APC) gene testing was performed in 14 of the 16 cases. The average age of diagnosis for FAP and thyroid carcinoma was 29 years (range 17-52 years) and 33 years (range 17-55 years), respectively. All FAP patients except 1 had more than 100 colonic adenomas. Extracolonic manifestations, beside thyroid cancer, were presented in 81% (n = 13) of the patients, including gastric and duodenal polyps, desmoid tumor, osteoma, epidermoid cyst, sebaceous cyst and lipoma. Colorectal cancer was diagnosed in 38% (n = 6) of the patients. The pathology of the FAP associated thyroid cancer was predominantly papillary carcinoma. Germline mutations were identified in 12 of 14 patients tested. Mutations proximal to the mutation cluster region (1286-1513) were detected in 9 cases. Thyroid cancer in our FAP population was rare, predominantly in females and showed papillary carcinoma histology. Additionally, thyroid cancer in our patients occurred in the setting of classic FAP phenotype. Germline mutations were located predominantly outside the APC mutation cluster region.

Colorectal cancer risk perception on the basis of genetic test results in individuals at risk for Lynch syndrome.

PURPOSE: Lynch syndrome is associated with inherited germline mutations in mismatch repair (MMR) genes. Genetic testing in high-risk individuals may yield indeterminate results if no mutation is found or if a mutation of unclear pathogenic significance is observed. There are limited data regarding how well patients with Lynch syndrome understand the clinical implications of genetic test results. This study examines colorectal cancer (CRC) risk perception in individuals tested for MMR mutations and identifies the factors associated with an appropriate interpretation of their cancer risk. PATIENTS AND METHODS: A total of 159 individuals who met the Revised Bethesda Guidelines and had previously undergone genetic testing completed a questionnaire eliciting demographic data, cancer history, genetic test results, and an estimate of their CRC risk. Associations between clinical factors, genetic test results, and CRC risk perception were explored using multivariable analyses. RESULTS: Of the 100 individuals with a pathogenic mutation (true positive), 90 (90%) correctly estimated their CRC risk as "high" or "very high" compared with other individuals their age. However, only 23 (62%) of 37 individuals with an indeterminate genetic test result correctly estimated their risk. Individuals with a history of Lynch syndrome-associated cancer (odds ratio [OR], 0.1; 95% CI, 0.1 to 0.6) or indeterminate genetic test results (OR, 0.2; 95% CI, 0.1 to 0.6) were significantly less likely to estimate their CRC risk as increased. CONCLUSION: Patients at risk for Lynch syndrome with an indeterminate genetic test result may be falsely reassured. It is important that health care providers continue to discuss the implications of uninformative results on lifetime cancer risk.

Low rate of microsatellite instability in young patients with adenomas: reassessing the Bethesda guidelines.

BACKGROUND AND AIM: Screening adenomas for microsatellite instability (MSI) in patients younger than 40 yr of age has been recommended by the Bethesda Guidelines as a means of identifying patients at risk for hereditary nonpolyposis colorectal cancer (HNPCC). We sought to determine the rate of MSI in adenomas removed from individuals under 40 yr of age over a 5-yr period in a university general gastroenterology practice. METHODS: We identified patients between 18 and 39 yr of age with endoscopically removed adenomatous colorectal polyps. Patients with polyposis syndromes, inflammatory bowel disease, or colorectal carcinoma were excluded. A three-generation family history was obtained via telephone interview. Endoscopic and histology reports were reviewed. Adenomas were tested for MSI using the BAT26 and BAT40 microsatellite markers, and expression of the MSH2 and MLH1 proteins was assessed by immunostaining. RESULTS: A total of 34 patients had 46 adenomas removed endoscopically. Out of 34 patients, 14 (41%) had a family history of colorectal cancer and 3 were from Amsterdam criteria positive families. A total of 28 of 46 adenomas (61%) were distal to the splenic flexure. Polyps ranged in size from 2 to 20 mm and averaged 6.6 mm. Five polyps (11%) were tubulovillous adenomas, and the remainder were tubular adenomas. None of the polyps were serrated adenomas and none demonstrated high-grade dysplasia. Among the 40 adenomas available for testing, none demonstrated MSI using either BAT26 (0/40) or BAT40 (0/21), nor did any of the polyps tested demonstrate loss of either MSH2 or MLH1 expression (0/16). CONCLUSION: Screening adenomas from patients younger than 40 yr of age for MSI was ineffective in identifying potentially new cases of HNPCC. New strategies that improve on the current clinical and molecular screening methods should be developed so that at-risk individuals can be identified and referred for germline testing before developing their first cancer.

Hereditary nonpolyposis colorectal cancer in young colorectal cancer patients: high-risk clinic versus population-based registry.

BACKGROUND & AIMS: Early onset colorectal cancer (CRC) is an important feature of hereditary nonpolyposis colorectal cancer (HNPCC). We sought to compare rates of genetically defined HNPCC among individuals with early onset CRC drawn from a high-risk clinic and a population-based cancer registry. METHODS: Probands with CRC diagnosed before 36 years of age were enrolled from a high-risk CRC clinic at the University of California, San Francisco (UCSF), and a population-based Kaiser Permanente (KP) Health Plan cancer registry. Probands provided cancer family histories and tumors for microsatellite instability (MSI) testing and MSH2/MLH1 protein immunostaining. Germline MSH2 and MLH1 mutational analysis was performed. RESULTS: Forty-three probands were enrolled from UCSF and 23 from KP. The UCSF and KP probands had similar median age of onset of CRC (30 vs. 31 years) and the percentage with any personal or family history of another HNPCC-related cancer (70% vs. 74%). However, 28 of 40 (70%) of the UCSF tumors were MSI-H compared with 6 of 18 (33%) of KP tumors (P = 0.01), and 13 germline MSH2 or MLH1 mutations were found in the UCSF group compared with 0 in the KP group (P = 0.0001). In a multivariate analysis, institution (P = 0.002) and the total number of colorectal cancers in the family (P = 0.0001) were independent predictors of MSH2 or MLH1 mutation. CONCLUSIONS: Family history of cancer is an important feature of HNPCC, even among individuals with early onset CRC. Caution must be undertaken when extrapolating data regarding HNPCC from high-risk clinic populations to the general population.