Abstract
Abstract Background: None of population-based epidemiological studies to date had a large enough sample size to show familial risk of testicular cancer (TC) by patients’ and their relatives’ age at diagnosis and also by rare histological subtypes. Objective: We aimed to estimate absolute and relative risk of TC in relatives of TC patients by age at diagnosis in patients and their relatives and histology subtypes. Design: A joint population-based cohort study. Setting and Participants: A cohort of 97,402 first-degree relatives of 21,254 TC patients who were diagnosed between1955 and 2010 in five European countries was followed for cancer incidence. Outcome Measurements and Statistical Analysis: Standardized incidence ratios (SIRs) were estimated using histology-, age-, period-, and country-specific incidence rates as the reference. The lifetime cumulative risks also were calculated. Results and Limitations: The lifetime cumulative risk of TC in brothers of a patient with TC was 2.3%, which represents 4-fold increased risk (SIR = 4.1, 95%CI = 3.6-4.6) over the general population risk. TC in a father increased the risk up to 2-fold in his son (95%CI = 1.7-2.4; lifetime risk 1.2%) and vice versa. When there were ≥2 TC patients diagnosed in a family, lifetime TC risk for relatives was 10-11%. Depending on age at diagnosis, twins had 9-74% lifetime risk of TC. Family history of most of the histological subtypes of TC increased the risk for concordant and most of the discordant subtypes. There was a tendency toward concordant age at diagnosis of TC among relatives. Conclusions: This study provides clinically relevant age-specific cancer risk estimates for family members of TC patients. Familial TC cases tended to develop TC at an age close to age at diagnosis of TC among their relatives, which is the novel finding of this study. Citation Format: Elham Kharazmi, Kari Hemminki, Eero Pukkala, Kristina Sundquist, Laufey Tryggvadottir, Steinar Tretli, Jørgen H. Olsen, Mahdi Fallah. Cancer risk in relatives of testicular cancer patients by histology type and age at diagnosis: a joint study from five Nordic countries. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2743. doi:10.1158/1538-7445.AM2015-2743
Published Version
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