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Men whose brothers have aggressive prostate cancer at increased risk
Men whose brothers had non-low-risk prostate cancer faced a significantly increased risk for developing an aggressive form of the malignancy, according to results of a study conducted in Sweden.
“Men with one or two first-degree relatives with prostate cancer have a two- to fivefold increased risk [for] being diagnosed with prostate cancer compared with men with no family history of prostate cancer, and the risk is also increased among men with second- and third-degree relatives with prostate cancer,” Fredrik Jansson, MD, a PhD student at Karolinska Institutet at Karolinska University Hospital in Stockholm, and colleagues wrote.
“Previous twin studies have assessed the concordance of a prostate cancer diagnosis but not the concordance of the type of prostate cancer,” they added. “If there is prognostic concordance within families, then knowledge of tumor characteristics and disease development among relatives may be helpful when counseling men with suspected or newly diagnosed prostate cancer.”
The researchers used the Swedish Prostate Cancer Database to identify 4,262 sets of brothers who both were diagnosed with prostate cancer.
Jansson and colleagues categorized cancers as either low risk (Gleason score, 6 or lower; clinical stage, T1 to T2; PSA, 10 ng/mL or less) or non-low risk. They used logistic regression to calculate odds ratios for concordance of non-low-risk cancer among monozygotic twins, dizygotic twins, full brothers and half brothers.
After adjusting for year of diagnosis and age, the highest concordance of non-low-risk disease occurred among monozygotic twins (OR = 3.82; 95% CI, 0.99-16.72). Full brothers also had a significant concordance (OR = 1.21; 95% CI, 1.04-1.39). These results persisted when researchers restricted analysis to brothers diagnosed within 4 years of each other.
Monozygotic twins had a significantly shorter median time between diagnoses than other groups (1.1 years) than full brothers (3.2 years; P < .001), dizygotic twins (2.8 years; P < .014), paternal half brothers (4.1 years; P < .001) and maternal half brothers (3 years; P < .003).
“We hypothesized a priori a concordance of non-low-risk prostate cancer among brothers in general, and among monozygotic twins in particular,” the researchers wrote. “Our data support this hypothesis, although with wide confidence intervals and a borderline significant estimate for monozygotic twins. Our results suggest that a man whose brother has been diagnosed with a non-low-risk prostate cancer is at a clinically relevant increased risk [for] developing an aggressive prostate cancer himself.” – by Andy Polhamus
Disclosures: Jansson reports no relevant financial disclosures. One author reports consultant or advisory roles with Astellas and Bayer.