BRCA1 and breast carcinoma: This lower relative risk is consistent with a general pattern of a lower relative risk in a higher risk population, as seen in the lower relative risk for contralateral breast cancer than first breast cancer in the general population,19 and the lower relative risk for the first cancer in BRCA1/2 heterozygotes than in the general population.24 The attenuated estimate might be explained by several factors, some of which are speculative.