Table 1. Relative Risk (RR) Related to Family History of Prostate Cancera
|Risk Group||RR for Prostate Cancer (95% CI)|
|CI = confidence interval; FDR = first-degree relative.|
|a Adapted from Kiciński et al.|
|Brother(s) with prostate cancer diagnosed at any age||3.14 (2.37–4.15)|
|Father with prostate cancer diagnosed at any age||2.35 (2.02–2.72)|
|OneaffectedFDR diagnosed at any age||2.48 (2.25–2.74)|
|Affected FDRs diagnosed <65 y||2.87 (2.21–3.74)|
|Affected FDRs diagnosed ≥65 y||1.92 (1.49–2.47)|
|Second-degree relativesdiagnosed at any age||2.52 (0.99–6.46)|
|Two or more affected FDRs diagnosed at any age||4.39 (2.61–7.39)|
Among the many data sources included in this meta-analysis, those from the Swedish population-based Family-Cancer Database warrant special comment. These data were derived from a resource that contained more than 11.8 million individuals, among whom there were 26,651 men with medically verified prostate cancer, of which 5,623 were familial cases. The size of this data set, with its nearly complete ascertainment of the entire Swedish population and objective verification of cancer diagnoses, should yield risk estimates that are both accurate and free of bias. When the familial age-specific hazard ratios (HRs) for prostate cancer diagnosis and mortality were computed, as expected, the HR for prostate cancer diagnosis increased with more family history. Specifically, HRs for prostate cancer were 2.12 (95% CI, 2.05–2.20) with an affected father only, 2.96 (95% CI, 2.80–3.13) with an affected brother only, and 8.51 (95% CI, 6.13–11.80) with a father and two brothers affected. The highest HR, 17.74 (95% CI, 12.26–25.67), was seen in men with three brothers diagnosed with prostate cancer. The HRs were even higher when the affected relative was diagnosed with prostate cancer before age 55 years.
A separate analysis of this Swedish database reported that the cumulative (absolute) risks of prostate cancer among men in families with two or more affected cases were 5% by age 60 years, 15% by age 70 years, and 30% by age 80 years, compared with 0.45%, 3%, and 10%, respectively, by the same ages in the general population. The risks were even higher when the affected father was diagnosed before age 70 years. The corresponding familial population attributable fractions (PAFs) were 8.9%, 1.8%, and 1.0% for the same three age groups, respectively, yielding a total PAF of 11.6% (i.e., approximately 11.6% of all prostate cancers in Sweden can be accounted for on the basis of familial history of the disease).