Increased Risk of Digestive and Genitourinary Primary Malignancies in Childhood Cancer Survivors

Rosie Amerikanou, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0SP

The British Childhood Cancer Survivor Study studied the potential between childhood cancer and subsequent primary neoplasm (SPN) in 17981 individuals who survived cancer after being diagnosed before the age of 15 and were treated between 1940-1991. All types of cancer were studied apart from nonmelanoma skin cancers and non-glioma CNS tumours as there is an under-ascertainment in their registration in the general population. Furthermore, all types of bladder tumours were included as their malignant potential is hard to classify.

To contrast SPN rates in survivors with those of the general population, standardised incidence ratio (SIR = Observed / Expected number of neoplasms) and Absolute Excess Risk (AER= average excess number of SPN observed / 10 000 survivors per year) were computed.

After an average of 25.6 years, 1354 SPNs were noted. The highest incidence show tumours of the:

  • Central nervous system (n = 344)
  • Nonmelanoma skin cancer (n = 278)
  • Digestive tract (n = 105)
  • Genitourinary (n = 100)

The study concludes that survivors have an increased risk of developing a SPN above 40 years of age. The cumulative percentage of survivors developing a neoplasm increased from 1.6% at age 20 to 13.8% at age 60 (versus the 8.4% expected in the general population). The AER at over 40 years is highest for digestive and genitourinary neoplasms.

The risk of colorectal cancer in survivors treated with abdominopelvic radiation is similar with people with 2 first-degree relatives affected (1.2%). In the latter group routine colonoscopy is currently being considered. Therefore it could be justifiable to offer routine colonoscopy to survivors.

Concerning the genitourinary malignancies, survivors of heritable retinoblastoma had an exceptional high risk with SIR (7.9) and multivariable Poisson regression revealed that females were at 70% higher risk.

A limitation of the study is the absence of detailed data on the radiotherapy and chemotherapy exposures. Also, the treatments occurred between 1940-1991, thus data may not reflect the effect of better treatments of recent years as in the case of more targeted radiotherapy regimes.

References: 

1. Reulen R.C. , Frobisher C. , Winter D.L. et al. ; Long-term Risks of Subsequent Primary Neoplasms Among Survivors of Childhood Cancer. JAMA 2011;305(22):2311-2319.
doi:10.1001/jama.2011.747

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