Biomedical subjects
H T Lynch
Publications and source records attributed to H T Lynch.
Desmoid tumors: genotype-phenotype differences in familial adenomatous polyposis--a nosological dilemma.
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Genetic counseling in hereditary nonpolyposis colorectal cancer: an extended family with MSH2 mutation.
OBJECTIVES: Molecular genetic advances have increased the demand for DNA testing. We describe DNA based genetic counseling in a hereditary nonpolyposis colorectal cancer (HNPCC) family. METHODS: This extended HNPCC family was found to harbor the MSH2 germline mutation. Family history, medical, and pathology documents enabled us to secure a high degree of verification that the kindred qualified as HNPCC. DNA testing revealed the MSH2 germline mutation that was verified independently in two laboratories. Genetic counseling was provided before DNA testing and disclosure of MSH2 findings. RESULTS: Genetic counseling revealed a variety of findings characterized by emotional stress in MSH2 germline mutation carriers. Concerns centered around reproductive issues, potential transmission of the deleterious gene to their progeny, and discrimination by insurance carriers and employers. More than one-half of the patients found to harbor the MSH2 mutation considered the option of prophylactic subtotal colectomy. CONCLUSION: DNA testing should be restricted to well-verified candidate families in which genetic counseling should be mandatory. HNPCC family members sought genetic risk assessment for their own health and that of their children. Contrasting emotional responses took place when told of their gene testing status and this required a sensitive empathetic listening ear. Patients have many concerns about their lifetime cancer destiny when told that they harbor the culprit MSH2 germline mutation.
Surgery, desmoid tumors, and familial adenomatous polyposis: case report and literature review.
OBJECTIVES: To demonstrate the role of surgical trauma in desmoid tumor formation in Gardner's syndrome. METHODS: Literature review indicates that desmoid tumors are exceedingly common in familial adenomatous polyposis (FAP) where the comparative risk is 852 times that of the general population. Prior abdominal surgery has been found in as many as 68% of FAP patients with abdominal desmoids. Fifty-five percent develop these lesions within 5 yr of their surgery. We describe a patient with Gardner's syndrome complicated by a desmoid tumor. RESULTS: This patient underwent a prophylactic colectomy at age 14, and 3 yr later developed intra-abdominal desmoid tumors unresponsive to radiation therapy, surgical excision, Sulindac, and tamoxifen therapy. The desmoids became massive and were inoperable. However, they showed an apparent complete response to a chemotherapeutic regimen of doxorubicin (90 mg/m2) and dacarbazine (900 mg/m2) in divided doses over 4 days of continuous infusion every 28 days. Because CT scans could not confirm this complete response, laparoscopy was performed. However, within a matter of only several months, desmoid tumors began developing in each of the three trocar sites, became massive and inoperable, and led to the death of this patient. CONCLUSION: These findings provide convincing evidence of the association between surgical trauma and the occurrence of desmoid tumors in patients with Gardner's syndrome.
Attenuated familial adenomatous polyposis (AFAP). A phenotypically and genotypically distinctive variant of FAP.
BACKGROUND: The usual manifestation of familial adenomatous polyposis (FAP) is hundreds or thousands of colonic adenomas. The authors previously described a colon cancer-prone syndrome characterized by fewer adenomas (1-100), most located in the proximal colon, and upper gastrointestinal lesions, particularly fundic gland polyps and duodenal adenomas. The colonic adenomas are often flat rather than polypoid, a feature emphasized in earlier reports with the term "hereditary flat adenoma syndrome." The syndrome has an autosomal dominant pattern of inheritance and is linked to the adenomatous polyposis coli (APC) locus at 5q. METHODS: This is a descriptive study based on one family that was followed for more than a decade. Total cell RNA was isolated from cultured lymphoblasts, and an in vitro protein synthesis assay was used to detect APC mutations. Sixteen individuals whose APC mutation status was known had sequential endoscopic evaluations. Five patients were given one or more courses of sulindac. RESULTS: There was perfect concordance between clinical affected status and an APC mutation. All affected members generated a 16-kDa polypeptide from the mutant allele, consistent with a 2-base pair deletion at the extreme 5' end of the APC gene. Sixteen mutation-positive individuals underwent upper gastrointestinal endoscopy and colonoscopy; 13 had colonic adenomas, with the number visualized at any one examination ranging from 1 to greater than 50. Upper gastrointestinal examination revealed fundic gland polyps in 15, gastric or duodenal adenomas in 4, and periampullary carcinoma in 1. CONCLUSION: AFAP is a phenotypically distinctive syndrome, differing from classic FAP by having fewer colonic adenomas that tend to be proximally distributed and flat rather than polypoid. The position of the APC germline mutation appears to allow for the molecular differentiation between FAP and the attenuated variant in that the extreme 5' APC mutations are associated with the latter.
Family history of cancer.
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The human plakoglobin gene localizes on chromosome 17q21 and is subjected to loss of heterozygosity in breast and ovarian cancers.
The gene encoding human plakoglobin was mapped to chromosome 17q12-q22. An intragenic restriction fragment length polymorphism was used to localize the plakoglobin gene distal to locus KRT10 and proximal to the marker D17S858. The plakoglobin gene colocalizes with the polymorphic 17q21 marker UM8 on the same cosmid insert. This subregion of chromosome 17 is known to be particularly subjected to genetic alterations in sporadic breast and ovarian tumors. We show loss of heterozygosity of the plakoglobin gene in breast and ovarian tumors. We have identified a low-frequency polymorphism in the plakoglobin coding sequence which results in an arginine to histidine substitution at amino acid position 142 of the protein, as well as a silent mutation at nucleotide position 332 of the coding sequence. This polymorphism allowed us to demonstrate an allelic association of plakoglobin with predisposition to familial breast and ovarian cancers. Our results, together with the present knowledge about the biological function of plakoglobin, suggest that plakoglobin might represent a putative tumor suppressor gene for breast and ovarian cancers.
Malignant breast epithelium selects for insulin-like growth factor II expression in breast stroma: evidence for paracrine function.
Paracrine interactions between stromal and epithelial cells are important influences on the growth and malignant behavior of breast cancers. Insulin-like growth factors I and II (IGF-I and II) are expressed by fibroblasts in benign and malignant breast lesions, and both are strong mitogens for a number of breast cancer epithelial cell lines in vitro. We have analyzed the stromal mRNA expression of IGF-I and IGF-II in matched sets of fibroblast cell lines derived from three locations in the affected breast of eight patients with breast cancer: (a) the breast tumor itself; (b) surrounding normal breast tissue; and (c) overlying breast skin. IGF-I expression was easily detected in all fibroblasts derived from normal breast tissue. In general, lesser amounts of IGF-I mRNA were detected in fibroblasts derived from breast tumors or skin. In contrast, IGF-II expression was detected at very low levels in only 3 of 8 normal breast fibroblasts, but was present in 6 of 8 tumor fibroblasts. IGF-II mRNA was expressed in all skin fibroblasts tested. IGF-II-negative stromal fibroblasts from normal breast, which were plated at low density and allowed to grow to confluence in the presence of MCF-7 breast tumor epithelial cells, demonstrated a marked increase in IGF-II mRNA expression. IGF-II in situ hybridization studies confirmed that IGF-II expression is seen at high levels in stroma of many invasive breast cancers but not normal breast. We conclude that paracrine influences, mediated by soluble factors released by breast tumor epithelium, are able to specifically increase expression of IGF-II in breast stroma, most likely by a process of clonal selection.
Rectal cancer after prolonged sulindac chemoprevention. A case report.
BACKGROUND: Sulindac is reported to induce regression of colonic adenomas. However, its role as a chemoprophylactic agent for people with familial adenomatous polyposis (FAP) is under consideration. METHODS: This case report describes a patient with FAP in whom rectal adenocarcinoma developed 37 years after prophylactic colectomy and 15 months after beginning a course of sulindac. She received endoscopic follow-ups every 3 months during 15 months of 150-mg twice-daily sulindac administration. At 12 months, an endoscopic examination was unremarkable; at 15 months, endoscopic examination revealed several polyps and a flat ulcerated lesion. RESULTS: Rectal carcinoma developed in a patient 15 months after beginning chemoprophylaxis: there was metastatic adenocarcinoma in 6 of 20 perirectal lymph nodes. In addition to the carcinoma, rectal mucosa contained two adenomas and multiple foci of adenomatous changes in flat mucosa. CONCLUSION: Sulindac may not alter the pathogenesis of FAP. Patients undergoing sulindac chemoprevention must be monitored closely, including endoscopic examination. Endoscopic surveillance should include an aggressive biopsy approach because the absence of polyps does not prove the absence of neoplastic change.
Insurance adjudication favoring prophylactic surgery in hereditary breast-ovarian cancer syndrome.
Insurance payment to cover costs of prophylactic surgery is occasionally denied to patients who may be at inordinately high risk for hereditary cancer. We describe a 43-year-old woman from a hereditary breast-ovarian cancer (HBOC) family which showed linkage to BRCA1 and who was at inordinately high risk for cancer but who was denied insurance coverage for prophylactic oophorectomy, despite strong recommendations by her gynecologist and a cancer geneticist-medical oncologist. The insurance company claimed that the surgery was not medically necessary because the woman's condition (hereditary cancer predisposition) was not an illness. A summary judgment issued by the Douglas County (Nebraska) District Court ruled in favor of the denial decision of Blue Cross/Blue Shield. But on appeal, the Nebraska Supreme Court offered the conclusion that the patient did in fact require this prophylactic surgery and overruled the District Court's decision for denial. The litigation provides the basis for this case report and may provide a precedent for insurance coverage for patients at high risk for hereditary forms of cancer.
Breast cancer and importance of zygosity determination in triplet sisters.
This study is the first to examine the genetic risk in a breast cancer-prone family wherein two of three triplet sisters and their mother manifested breast cancer. The unaffected triplet, the proband, was found to be monozygotic with her deceased sister through DNA testing of tumor blocks and dizygotic to her living affected sister. Genetic counseling implications are discussed.
Expression of two mucin antigens in cultured human ovarian surface epithelium: influence of a family history of ovarian cancer.
OBJECTIVE: The genetic changes in hereditary ovarian cancer syndromes suggest that the phenotype of ovarian surface epithelium in women with familial ovarian cancer might be altered. To test this hypothesis, we compared two tumor markers, CA 125 and 2G3, in cultures of overtly normal epithelium from patients with and without familial ovarian cancer. STUDY DESIGN: Surface epithelia from 18 patients with no family history of ovarian cancer, five with family histories that were insufficient to be classified as familial, and seven with strong family histories were examined by immunofluorescence, immunocytochemistry, and radioimmunoassay. The influence of cell density, morphologic features, propagation in culture, and immortalization with SV40 on the expression of the markers was investigated. RESULTS: CA 125 occurred in cells with epithelial rather than atypical morphologic features. In cultures with no family history and minor family history, CA 125 was present in up to 45% cells in passage 1 but in only < 5% cells in 14 of 16 cultures by passages 3 to 4. In contrast, nine of 10 cultures with family history retained > 5% CA 125-positive cells in passages 3 to 4. This prolonged presence of CA 125 correlated with a persisting epithelial phenotype, whereas most cells with no family history and minor family history became atypical by passage 3. Immortalization eliminated CA 125 in all three types of cells. 2G3 bound to few cells in low passage, independent of family history and morphologic features. The proportion of 2G3-expressing cells increased significantly with immortalization in all cultures, independent of family history. Ovarian carcinoma lines expressed both markers. CONCLUSION: In cultures of ovarian surface epithelium 2G3 expression increases with immortalization, whereas CA 125 is lost with immortalization but correlates with epithelial cell morphologic features and with family history. The results suggest that there may be phenotypic changes in overtly normal ovarian surface epithelium of women with family histories of ovarian cancer.
Genetics and environment in Hodgkin's disease.
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Colonoscopy in relation to the evolving genetics of familial colorectal cancer.
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A large multisite cancer family is linked to BRCA2.
We identified a large French-Canadian family with 21 cases of breast cancer, including two affected brothers. Segregation of markers from chromosome 13q in this family showed linkage to the BRCA2 gene locus (lod = 3.67 at D13S289). A number of cancers of other types occurred in this family, including three cases of prostate cancer and two cases of lymphoma. The penetrance of breast cancer among BRCA2 carriers is estimated to be 75% to the age of 70.
Medical genetic study of eight pancreatic cancer-prone families.
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Creighton University to open hereditary cancer prevention clinic.
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Genetics, natural history, surveillance, management, and gene mapping in the Lynch syndrome.
Hereditary nonpolyposis colorectal cancer (HNPCC), also termed Lynch syndrome, may account for as much as 10-15 percent of the total colorectal burden. Lynch syndrome I is characterized by site-specific colorectal cancer (CRC) with early (congruent to age 45) onset, predilection to the proximal colon (congruent to 70%), and a marked susceptibility to metachronous CRC (45% following hemicolectomy or segmental resection). Lynch syndrome II shows the same colonic features but includes an excess of extra-colonic CRCs, namely carcinoma of the endometrium, ovary, small bowel, stomach, pancreas and transitional cell carcinoma of the ureter and renal pelvis. These findings form the basis for our surveillance recommendations: full colonoscopy initiated at age 25 and repeated every other year, and, in Lynch syndrome II variant, biannual endometrial aspiration biopsy. Screening for the remaining cancer types is dependent upon the availability of screening modalities and the pattern of cancer expression within specific families. The excess of metachronous CRC mandates that subtotal colectomy be performed for any CRC. The lack of premonitory physical stigmata has forced clinicians to diagnose HNPCC based on the family history in concert with the natural history features of the cancer phenotype within the pedigree. Problems with this approach include variable gene penetrance, the fact that cancer affected may or may not be gene carriers, death of gene carriers prior to developing cancer, and difficulty with pathology verification of tumor site and type. Partial resolution of these problems is possible now that HNPCC has been linked to chromosomes 2p and 3p and the susceptibility gene at chromosome 2p has been cloned.(ABSTRACT TRUNCATED AT 250 WORDS)