Lack of referral for genetic counseling and testing in BRCA1/2 and Lynch syndromes: a nationwide study based on 240,134 consultations and 134,652 genetic tests

Based on nationwide data from the French national cancer institute (INCa), we analyzed the evolution of cancer genetics consultations and testing over time, and the uptake of targeted tests in relatives of families with BRCA1/2 or MMR genes mutation. Genetic testing and consultations for familial high-risk individuals are exclusively funded and monitored by the INCa in France. All nationwide cancer genetics centers reported annually standardized parameters of activity from 2003 to 2011. The analysis included a total of 240,134 consultations and 134,652 genetic tests enabling to identify 32,494 mutation carriers. Referral for hereditary breast and ovarian cancer (HBOC) or colorectal cancer predisposition syndromes represented 59 % (141,639) and 23.2 % (55,698) consultations, respectively. From 2003 to 2011, we found a dramatic and steady increase of tests performed for BRCA1/2 (from 2,095 to 7,393 tests/year, P < 0.0001) but not for MMR genes (from 1,144 to 1,635/year, P = NS). The overall percentage of deleterious mutations identified in the probands tested was 13.8 and 20.9 % in HBOC and Lynch syndromes, respectively. Pooled analysis for BRCA1/2 and Lynch syndrome tests showed an inverse relationship between the percentage of mutation detected and the absolute number of tests performed over the time (overall Cochran-Armitage test for trend: P < 0.001). In families with BRCA1/2 or MMR identified mutations, there was an average number of 2.94 and 3.28 relatives performing targeted tests, respectively. This nationwide study shows a lack of referral and genetic testing in Lynch as compared to HBOC syndromes. Only a third of relatives of a proband with a predisposing mutation performed a targeted test. Enhanced information about benefit of genetic testing should be given to clinicians and patients for Lynch syndrome and relatives of a proband carrying an identified predisposing mutation.

Influence of loco-regional radiation therapy on subsequent cancer risk among BC pts with p53 germline mutations

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Background: The management of breast cancer (BC) patients (pts) with germline p53 mutations, a rare genetic condition, is not the object of specific recommendations. Preclinical data and preliminary clinical observations suggest a theoretically major radio-sensitivity and high risk of secondary radio-induced malignancies. It remains discussed whether the knowledge of a germline p53 mutation may influence treatment (trt) choices and have prognostic importance. We reviewed our cohort of BC diagnosed as first tumor in pts with germline p53 mutations within the past 11 years, with an attempt to describe secondary malignancies occurring after trt of primary tumor. Patients and Methods: 9 pts have been diagnosed and treated in our institution within the past 11 years for BC as first tumor in the context of a documented germline p53 mutation. Their tumor characteristics, treatment and follow-up data were extracted from prospectively-registered medical records. Results: Median age at diagnosis of primary BC was 32 (22–48). 7/9 pts had a family history compatible with Li Fraumeni syndrome, while 2 had no family history. No pt had previous knowledge of her p53 mutation. Primary tumors were ductal carcinoma in situ (4), infiltrating ductal carcinoma (4), phyllode tumor (1). 3 pts had conservative surgery and 6/9 underwent mastectomy (M). 6 received loco-regional radiation therapy (RT). None had prophylactic contra lateral mastectomy. Loco-regional (LRR) and contra-lateral relapses are listed in the Table , as well as incidence of second primaries within or outside radiation field. Second primaries were sarcoma in 3/4 cases and 1 was papillary thyroid carcinoma. Conclusions: Because of high risk of second breast primary and probably very high risk of radio-induced breast cancer, BC pts with germline p53 mutations should be advised bilateral prophylactic mastectomy and avoidance of radiation therapy. In this context, the knowledge of the mutation might be of great importance. [Table: see text]

No significant financial relationships to disclose.

Molecular basis of the Li-Fraumeni syndrome: an update from the French LFS families

We have performed an extensive analysis of TP53 in 474 French families suggestive of Li-Fraumeni syndrome (LFS), including 232 families fulfilling the Chompret criteria. We identified a germline alteration of TP53 in 82 families (17%), in 67/232 of the families fulfilling the Chompret criteria (29%) and in 15/242 which did not fulfil these criteria (6%). Most of the alterations corresponded to missense mutations (67%), and we identified in four families genomic deletions removing the entire TP53 locus, the promoter and the non-coding exon 1, or exons 2-10. These results represent a definitive argument demonstrating that LFS results from TP53 haplodeficiency. The mean ages of tumour onset were significantly different between patients harbouring TP53 missense mutations and other types of alterations, missense mutations being associated with a 9 year earlier tumour onset. These results confirm that missense mutations not only inactivate p53 but also have an additional oncogenic effect. Germline alterations of TP53 that lead exclusively to loss of function are therefore associated with a later age of tumour onset and the presence of such mutations should be considered in atypical LFS families with tumours diagnosed after 40 years.

Mutation du gène CDKN2A et perte d’activité de la protéine p16 chez un malade traité par L-Dopa et atteint de mélanomes sporadiques multiples

BACKGROUND

Cutaneous melanoma is a complex disease involving genetic and environmental factors. Levodopa has been incriminated in the development and/or progression of melanoma.

OBSERVATION

We report the case of a man treated with levodopa and a dopadecarboxylase inhibitor for Parkinson's disease and presenting 22 cutaneous melanomas over a 4-year period. The patient is of phototype II and presents multiple nevi. Genetic analysis of predisposing genes demonstrated a CDKN2A mutation with loss of p16 activity.

DISCUSSION

Multiple melanomas may be associated with genetic predisposition, and screening for the latter should be performed. The exceptionally high number of melanomas developed by our patient raised suspicions about levodopa, a precursor in melanin synthesis, as a potential inducer. Increased dermatologic controls and screening for predisposing genetic factors appear to us to be warranted in the event of melanoma development in patients on levodopa.

Study of BRAF mutations in melanoma and nevi from patients with germline mutation in the CDKN2A gene

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Background: Germline mutations in the CDKN2A tumor suppressor gene is a rare condition associated with a high risk of melanoma. Somatic activating mutations of the BRAF gene are frequently observed in cutaneous melanoma (40–60%) but their occurrence vary according to melanoma subtypes (cutaneous, vs mucosal or uveal) and are less frequent in melanoma located on chronically sun-exposed skin. It is thought that melanomas occurring in patients carrier of a CDKN2A germline mutation are associated a second inactivating genetic event in the tumor, facilitating cellular transformation by loss of function this crucial gatekeeper of the G1-S checkpoint. However, the potential role of the MAP-kinase pathway, and more precisely, the involvement of BRAF activation, in this particular population of patients, are still unknown. Thus, our objective was to evaluate the frequency of BRAF somatic mutations in melanoma and nevi developed by patients carrier of a CDKN2A germline mutation. Methods: DNA was extracted from paraffin-embedded tissues of 36 primary melanomas, 9 metastases and 20 nevi from 31 patients with CDKN2A germline mutation. Ten sporadic melanoma from patients harbouring no CDKN2A mutation were also studied as a control population. BRAF mutations were screened by direct sequencing of exon 11 and 15. Results: BRAF mutations (V599E) were found with a significantly lower frequency of 14% (5/36) in melanomas from patients with proven CDKN2A germline mutation, as compared to a frequency of 55% (5/9) in patients with no genetic predisposition (two-sided Fishers exact test, p=0.02). Frequencies of BRAF mutations in metastases and nevi from patients with CDKN2A germline mutation were 33%(3/9) and 10% (2/20) respectively. Conclusions: BRAF mutations seem to be less frequent in melanoma from patients with familial predisposition harbouring CDKN2A germ line mutation than in sporadic melanoma. These results suggest that CDKN2A loss of function gives rise to tumorigenic pathways where genetic events distinct from BRAF activating mutation can induce cell transformation. Additional biological studies are performed on this rare population of melanoma samples in order to better characterize the specificity of cellular transformation in the context of CDKN2A germ line mutation.

No significant financial relationships to disclose.