Risk of a second cancer in Canadians diagnosed with a first cancer in childhood or adolescence

Abstract

BackgroundSecond cancers are an adverse outcome experienced by childhood cancer survivors. We quantify the risk and correlates of a second cancer in Canadians diagnosed with a first cancer prior to age 20 years.MethodsUsing death-linked Canadian Cancer Registry data, a population-based cohort diagnosed with a first cancer between 1992 and 2014, prior to age 20 years, were followed for occurrence of a second cancer to the end of 2014. We estimate standardized incidence ratios (SIR), absolute excess risks (AER), cumulative probabilities, and hazard ratios (HR).Findings22,635 people contributed 204,309•1 person-years of follow-up. Overall risk of a second cancer was 6•5 (95% CI: 5•8–7•1) times greater than expected resulting in an AER of 16•5 (14•4–18•5) cancers per 10,000 person-years and a 4•8% (3•8%–6•0%) cumulative probability of a second cancer at 22•6 years of follow-up. SIRs decreased with increasing age at diagnosis and time since diagnosis; were larger in more recent calendar periods of diagnosis; and varied by type of first cancer. Large SIRs in the first year after diagnosis and in those diagnosed in 2010–2014 were partly associated with changing registry practices. For the whole cohort, factors associated with the hazard of a second cancer included: being female vs. male [HR = 1•439 (95%CI: 1•179–1•760)]; being diagnosed in 2005–2014 vs. 1992–2004 [2•084 (1•598–2•719)]; having synchronous first cancers [4•814 (2•042–9•509)]; and being diagnosed with certain types of cancer. Factors varied, however, by type of first cancer.InterpretationRisks of a second cancer are not equally distributed and can be impacted by changes in registry practice and the methods used to define second cancers.

The Burden of Late Effects and Related Risk Factors in Adolescent and Young Adult Cancer Survivors: A Scoping Review

“…Studies investigating the development of any kind of SMN among a mixed-cancer population and reporting a single overall estimate for the standardized incidence ratio (SIR) found that AYA cancer survivors were 1.6 (95% confidence interval [95% CI]:1.6–1.6) to 4.3 (95% CI:3.6–5.1) times more likely to experience an SMN relative to that of a primary malignant neoplasm expected in the general population ( Table 1 ) [ 17 , 18 , 19 , 20 ]. Absolute excess risk (AER) for developing an SMN in these same cohorts ranged between 15.9 (95% CI:12.1–19.8) and 25.9 (95% CI not reported) per 10,000 person-years at risk.…”

Comparison Between Primary and Secondary Pediatric Mucoepidermoid Carcinoma of the Head and Neck

“…The prevalence and risk factors for SMNs have been introduced by many researchers. Zakaria et al ( 20 ) found that, among 22,635 people surviving childhood cancer, 395 patients had a secondary malignancy with an additional nearly fivefold risk than expected in the general population. The most common site was the thyroid, followed by the breast and oral cavity.…”

Second malignant neoplasms within 5 years from first primary diagnosis in pediatric oncology patients in Canada: a population-based retrospective cohort study

“…Since comprehensive examination at the first diagnosis can artificially inflate the risk of SMN in the first 60 days following a diagnosis, cancer diagnoses within 60 days of the first diagnosis were considered part of the initial diagnosis. This 60-day window has been used in other studies to decrease the risk of differential surveillance ( 16 , 21 , 22 ) into one of the seven main diagnostic types of childhood cancer ( Table 1 ) to mitigate small numbers of events. Only the first SMN was used to indicate a SMN as there were very few cases with multiple SMNs.…”