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Sweden was the first country to establish a nationwide breast cancer screening service. We used the Swedish Family-Cancer Database to evaluate the risk of invasive carcinoma after in situ carcinoma of the breast. Risk estimates for contralateral and ipsilateral invasive malignancies following age and histology specific in situ breast carcinomas were calculated using Poisson's regression analysis. The agreement between concordant and discordant morphologies of invasive and in situ breast cancer was measured using the kappa statistic. Women with in situ breast cancer showed a relative risk of 2.03 for contralateral and 3.94 for ipsilateral invasive breast cancer. The risk was higher for in situ carcinomas diagnosed before the age of 50 years and after lobular in situ breast cancers. A comparison of the risks during the past decades suggested that the risk of ipsilateral breast cancer has increased in Sweden but that of contralateral breast cancer has remained unchanged. In situ and the subsequent invasive breast cancers did not seem to share their morphologies. [ABSTRACT FROM AUTHOR]

A reliable determination of familial risks for cancer is important for clinical counseling, prevention and understanding cancer etiology. Family-based gene identification efforts may be targeted if the risks are well characterized and the mode of inheritance is identified. Medically verified data on familial risks have not been available for all types of cancer but they have become available through the use of the nationwide Swedish Family-Cancer Database, which includes all Swedes born in 1932 and later with their parents, totaling over 10 million individuals. Over 150 publications have emanated from this source. The familial risks of cancer have been characterized for all main cancers and the contribution of environmental and heritable effects to the familial aggregation has been assessed. Furthermore, the mode of inheritance has been deduced by comparing risks from parental and sibling probands. Examples are shown on familial clustering of cancers, for which heritable susceptibility genes are yet unknown, such as squamous cell carcinoma of the skin, intestinal carcinoids, thyroid papillary tumors, brain astrocytomas and pituitary adenomas. Some common cancers, such as lung and kidney cancers, appear to show an early-onset recessive component because familial risks among siblings are much higher than those in families where parents are probands. Many of the cancer sites showing high familial risks lack guidelines for clinical counseling or action level. In conclusion, we recommend that any future gene identification efforts, either using linkage or association designs, devise their strategies based on data from family studies. Clinical genetic counseling would benefit from reviewing established familial risks on all main types of cancer.

Background: Population-based data on the familial association of specific histologic types of ovarian malignancy with other malignancies are limited. Such data may help to elucidate etiologic differences among histologic types of ovarian malignancy., Methods: The nationwide Swedish Family-Cancer Database, which includes 10.3 million individuals and 20,974 ovarian carcinomas, was used to calculate standardized incidence ratios and 95% confidence intervals for age- and histology-specific ovarian malignancies in women whose parents or siblings were affected with malignancies at the most common disease sites., Results: Ovarian malignancy was found to be associated with ovarian, laryngeal, breast, endometrial, liver, and colon carcinoma, as well as myeloma; epithelial ovarian malignancy was found to be associated with ovarian, endometrial, and skin malignancies and with melanoma and myeloma; papillary serous cystadenocarcinoma was found to be associated with ovarian and skin malignancies and with myeloma; and endometrioid carcinoma was found to be associated with endometrial, ovarian, and prostate malignancies and with melanoma. For younger women (ages 40-45 years) whose mothers were affected with endometrial malignancies, the risk of developing endometrioid carcinoma was slightly greater than the risk of developing papillary serous cystadenocarcinoma., Conclusions: Specific types of ovarian malignancy may be associated with specific familial disease sites, with such associations depending on age at diagnosis; the strength of the observed associations varied according to histology. Associations were found between endometrioid carcinoma and endometrial malignancy and between serous carcinoma and Hodgkin disease., (Copyright 2004 American Cancer Society.)