Increased cancer risk in offspring of women with colorectal carcinoma

Family History of Cancer in Relation to Breast Cancer Subtypes in African American Women

BACKGROUND

The evidence on the relation of family history of cancers other than breast cancer to breast cancer risk is conflicting, and most studies have not assessed specific breast cancer subtypes.

METHODS

We assessed the relation of first-degree family history of breast, prostate, lung, colorectal, ovarian, and cervical cancer and lymphoma or leukemia, to the risk of estrogen receptor-positive (ER(+)), ER(-), and triple-negative breast cancer in data from the African American Breast Cancer Epidemiology and Risk Consortium. Multivariable logistic regression models were used to calculate ORs and 95% confidence intervals (CI).

RESULTS

There were 3,023 ER(+) and 1,497 ER(-) breast cancer cases (including 696 triple-negative cases) and 17,420 controls. First-degree family history of breast cancer was associated with increased risk of each subtype: OR = 1.76 (95% CI, 1.57-1.97) for ER(+), 1.67 (1.42-1.95) for ER(-), and 1.72 (1.38-2.13) for triple-negative breast cancer. Family history of cervical cancer was associated with increased risk of ER(-) (OR = 2.39; 95% CI, 1.36-4.20), but not ER(+) cancer. Family history of both breast and prostate cancer was associated with increased risk of ER(+) (3.40; 2.42-4.79) and ER(-) (2.09; 1.21-3.63) cancer, but family history of both breast and lung cancer was associated only with ER(-) cancer (2.11; 1.29-3.46).

CONCLUSIONS

A family history of cancers other than breast may influence the risk of breast cancer, and associations may differ by subtype.

IMPACT

Greater surveillance and counseling for additional screening may be warranted for women with a family history of cancer.

Familial risks for colorectal cancer show evidence on recessive inheritance

Recent molecular genetic data have become available on a recessive inheritance in colorectal cancer (CRC). We wanted to search for evidence for recessive inheritance from a population-based family data set, which is not sensitive to reporting or ascertainment bias. The nationwide Swedish Family-Cancer Database covered 10.3 million individuals whose invasive CRCs of adenocarcinoma histology were followed from 1991 to 2000. Age of the offspring and parental populations was limited to less than 69 years. Standardized incidence ratios (SIRs) were calculated for site-specific CRC in offspring whose parents or siblings were diagnosed with CRC. A total of 6,774 offspring were recorded with CRC, whose risk was 2.13 when a parent was diagnosed with CRC and it was 2.75 when a sibling was affected. The SIRs for right-sided colon cancer were 7.53 among siblings and 3.66 among offspring of affected parents, giving a 1.8-fold excess familial risk among siblings. Colon cancer among the 0- to 68-year-old population accounted for about 25% of all colon cancers. Examination of all cancers in family members of the affected siblings did not reveal large contribution by known syndromes, such as hereditary nonpolyposis colorectal cancer. The most likely explanation to the high risk of right-sided colon cancer among siblings is a recessive inheritance, which would account for 0.75% of all CRCs. Its high prevalence and predilection to right-sided colon suggest that only a small proportion of this familial aggregation could be due to MYH mutations.

Familial colorectal adenocarcinoma from the Swedish Family-Cancer Database

Familial risks for colorectal (CRC) adenocarcinoma were characterized from the Swedish Family-Cancer Database covering 9.6 million individuals, whose family relationships and cancers were obtained from registered sources, not sensitive to reporting or ascertainment bias. Cancer cases were retrieved from the Swedish Cancer Registry from years 1958-96. Standardized incidence ratios (SIRs) were calculated based on gender-, age-, period- and tumor type specific rates. A total of 4,794 and 67,925 CRCs were recorded in offspring and parents, respectively. For colon and rectal adenocarcinoma, the SIRs in offspring were 2.28 and 1.68 by parental CRC adenocarcinoma, giving attributable proportions of 6.45 and 3.31%, respectively. The SIR of CRC was over 10 when both offspring and parents were diagnosed at a young age. The risk for parental CRC adenocarcinoma was over 100 when 2 or more children were affected. The risk in siblings was also very high when a parent was affected. The familial cancer sites that associated with CRC were those typical of hereditary nonpolyposis colorectal cancer (HNPCC). This is the largest study published on familial CRC and the only one reporting specifically on adenocarcinoma. The data suggest that HNPCC is the largest single disease entity among CRCs, probably accounting for less than 50% of familial CRC. Other familial components appear heterogeneous, characterized by incomplete penetrance, recessive mode of inheritance and few associated tumor sites.