Concordance of Non–Low-Risk Prostate Cancer Among Brother Pairs


Key Points

  • Among brothers with prostate cancer, non–low-risk disease in one was associated with increased risk of non–low-risk disease in the other.
  • The concordance for non–low-risk disease was significant among full brothers. 

In a Swedish study reported in the Journal of Clinical Oncology, Jansson et al identified an increased risk of non–low-risk prostate cancer among men with prostate cancer who had with brothers diagnosed with non–low-risk disease.

Study Details

The study involved 4,262 pairs of brothers with prostate cancer in the Prostate Cancer Database Sweden. Low-risk cancers were defined as Gleason score ≤ 6, clinical stage T1–2, Nx/N0, Mx/M0, and prostate-specific antigen ≤ 10 ng/mL; all others were defined as non–low risk. The population with relevant available data included 3,556 full brothers, 38 paternal half-brothers, 45 maternal half-brothers, 57 monozygotic twins, and 34 dizygotic twins.

Concordance of Non–Low-Risk Disease

For index brothers with non–low-risk disease, the second brother was found to have non–low-risk disease for 1,419 full brother pairs (62%), 27 monozygotic twin pairs (64%), 8 dizygotic twin pairs (57%), 16 paternal half-brother pairs (70%), and 20 maternal half-brother pairs (59%). In analysis adjusting for age and year of diagnosis, the odds ratios for concordance for non–low-risk disease were 3.82 (95% confidence interval [CI] = 0.99–16.72) for monozygotic twins, 1.38 (95% CI = 0.27–7.29) for dizygotic twins, 1.21 (95% CI = 1.04–1.39) among full brothers, 2.47 (95% CI = 0.58–11.26) among paternal half-brothers, and 0.68 (95% CI = 0.13–3.24) among maternal half-brothers. Odds ratios were similar in analysis restricted to brothers who were diagnosed within 4 years.  Median time between diagnoses was significantly shorter for monozygotic twins (1.1 years) than for 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 (3.0 years, P < .003).

The investigators concluded, “Non–low-risk prostate cancer has a heritable pattern suggesting shared genetic factors, with the highest concordance among 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 of developing an aggressive prostate cancer himself.”

The study was supported by the Strategic Research Programme in Cancer (StratCan) at Karolinska Institutet, Swedish Cancer Society, and Foundation Johanna Hagstrand och Sigfried Linnérs Minne.

Fredrik Jansson, MD, of the Karolinska Institutet, Stockholm, is the corresponding author for the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.