Familial adenomatous polyposis (FAP) is a rare autosomal-dominant disease characterized by the development of more than 100 colorectal adenomatous polyps in young adults. In the absence of surgical intervention, colorectal cancer ineluctably develops in all affected patients. Recent progress in the isolation of the gene responsible for the disease allows to detect gene carriers before they present with symptoms attributable to polyps. Moreover, the presence of four or more lesions of congenital hypertrophy of the retinal pigment epithelium is an extracolonic manifestation of FAP allowing presymptomatic screening of this disease. An effective screening programme combined with the elaboration of a registry for FAP and prophylactic colectomy should reduce mortality related to colorectal cancer. Two other extracolonic manifestations of FAP remain major causes of death: abdominal desmoid tumors and duodenal adenocarcinoma. At this time, no effective medical or surgical therapy has been found to cure these lesions. Restorative proctocolectomy with ileal reservoir is another major advance. This procedure is now regarded as the treatment of choice for patients with FAP because radical removal of all premalignant colorectal mucosa eliminates the risk of subsequent development of a colorectal adenocarcinoma.

Chronic infection by hepatitis B and C viruses is frequently associated to the development of primary liver cancer. Liver cirrhosis, induced by these viral infection, plays an important role in the liver carcinogenesis. In addition, HBV has a direct role in liver cell transformation by a transactivating effect of some viral proteins as well as insertional mutagenesis. The role of hepatitis C virus is not known. The strong association, even in France, of primary liver cancer to these viral infections underline the importance of their prevention by vaccination.

Von Hippel-Lindau (VHL) disorder is an autosomal dominant disease characterized by the almost constant development of hemangioblastomas in the central nervous system (cerebellum, spinal cord and retina). In addition, various types of tumors including renal cell carcinomas, pancreatic cysts and pheochromocytomas are frequently observed in VHL gene carriers. Linkage of the VHL locus to the RAF-1 oncogene on the short arm of chromosome 3 (3p25-26) has been recently reported. Pheochromocytoma is of particular interest because of the risk of inaugural malignant hypertensive crisis but especially because of a great degree of interfamily variability (from 0 to 92% of affected members in previously reported large kindreds). We have studied a French series of 25 pheochromocytoma (11 males, 14 females) in VHL affected patients. Twenty pheochromocytoma (80%) occurred in a familial context, whereas 5 (20%) were consistent with "apparent sporadic cases". The mean age at pheochromocytoma diagnosis was 27 years (5-55 years). Bilateral tumours have been documented in 13 cases (52%). The prevalence of pheochromocytoma revealing VHL was 14 out 25 (56%). In these cases, VHL diagnosis was considered up to 25 years later. In 6 cases (2 deceased) pheochromocytoma was the only manifestation of VHL. Thus, search for VHL must be systematic in the presence of pheochromocytoma, in the interest of the patients themselves and of potential at-risk family members (prevention of hypertensive crisis linked to latent tumours). Basic check-up (neurological and somatic examination, ophthalmoscopy, familial inquiry) may be completed with cerebral CT scan or MRI and abdominal ultrasonography followed, if positive or doubtful, by abdominal MRI or selective angiography.

Described in Switzerland in the early '60, the major features of hereditary non-polyposis colon cancer syndrome (HNPCCS) were established 20 years ago by H. T. Lynch. HNPCCS accounts for at least 60% of the colon cancer etiology. Cancer family syndrome is defined by the presence of extracolonic primary tumors in addition to colon cancer. Both syndromes are transmitted by an autosomic dominant pattern. None of the known biomarkers are specific and/or sensitive enough to rely on their predictive values of patient's risks. A typical Swiss family was investigated on the basis of the cancer-prone family history. 21% of the family members observed over 5 generations presented one or more (30% of the cases) colo-rectal neoplasms at the age of 50. 55% of the tumors were right sided. Histologically, half of the tumors were mucinous. 30% of metachronous cancer appeared within 10 years. Polyps (1-3) and flat adenomas were associated to the lesion in 57%. Extra-colonic tumors appeared in 18% of family members and in half of the colon cancer patients. The sites of these tumors were the urinary tract, ovary, small bowel, breast and stomach. Two fibroblast strains of affected individuals were established. No increased tetraploidy was noted. Preliminary results suggest that this two strains are rather sensitive to ionising radiation. Often neglected, family history of colon cancer remains the major diagnostic and decision-making tool of a such syndrome. It will necessitate special treatment of affected subjects and early screening of the relatives.(ABSTRACT TRUNCATED AT 250 WORDS)

Among the different mechanisms of multidrug resistance, the overexpression of the mdr1 gene has been actively investigated during the last 5 years. This gene encodes a 170 kDa protein, named P-gp, a member of a transporter superfamily, the ABC (ATP Binding Cassette) proteins. P-gp actively expels out of the tumoral cell different drugs like anthracyclins, vinca alkaloids, epipodophyllotoxins. The involvement of mdr1 gene in clinical drug resistance is now demonstrated, and several trials using P-gp modulators and chemotherapy are going on in resisting tumors. Other intrinsic drug resistance mechanisms, such as increase of intracellular glutathione content or decrease of topoisomerase activity, could be involved in clinical drug resistance.

Recently, there has been a significant increase in the knowledge about the molecular basis of renal cell carcinoma. Its sporadic form is characterized by a deletion on the short arm of chromosome 3, even for localized stages. The same genetic abnormality is found in renal cell carcinomas associated with the von Hippel-Lindau disease. Such findings strongly suggest the presence of a common tumor suppressor gene which seems involved in the genesis of sporadic renal cell carcinoma and in the predisposition of hereditary cancers. Other tumor suppressor genes located on other chromosomes, as well as over expression of growth factors, seem to be related to the progression of this malignancy. Further studies of the molecular events associated with cellular transformation should help to better understand the behavior of such cancers and to find new therapeutical approaches.