A recent Canadian study suggests that survivors of childhood cancer are more likely to develop a second cancer.
Still considered rare, childhood cancer is the second-highest cause of death among Canadian children following injury-related death. On average, just over 900 children are diagnosed with cancer in Canada every year. Due to advances in diagnosis and treatment, 83% of children diagnosed with cancer in Canada will now survive.
Although the number of young cancer survivors is growing, previous research has shown that this population may be at risk of developing a second cancer. In order to quantify this risk, researchers looked back at children and youths under the age of twenty who were diagnosed with cancer between the years of 1992-2014. Published in  EClinicalMedicine, the study spanned over twelve of Canada’s thirteen jurisdictions including over 70% of the population.
Researchers gathered data from the Canadian Cancer Registry following 22,635 children looking for an occurrence of a second cancer. The presence of multiple cancers, sex, age of diagnosis, calendar period since diagnosis, time since diagnosis, and type of cancer were all analysed and considered when reviewing the statistics.
The risk of a childhood cancer survivor developing a second cancer was found to be 6.5 times greater than expected. For most cancers, the risk of reoccurrence decreases each year. When excluding multiple tumours from the second cancer count, 40% of second cancers were found to occur within the first five years of original diagnosis. Females were found to be at greater risk than males of developing a second cancer. This may be due to the higher incidence of breast and thyroid cancers occurring as a second cancer.
Further research is needed to investigate the risk factors for developing a second cancer.
Written by Helen Massy, BSc
References:
Kidscancercare.ab.ca. (2020). Stats – Kids Cancer Care. [online] Available at: https://www.kidscancercare.ab.ca/childhood-cancer/stats [Accessed 8 Jan. 2020].
www.cancer.ca. (2020). Childhood cancer statistics – Canadian Cancer Society. [online] Available at: https://www.cancer.ca/en/cancer-information/cancer-101/childhood-cancer-statistics/?region=on [Accessed 8 Jan. 2020].
Zakaria, D., Shaw, A. and Xie, L. (2019). Risk of a second cancer in Canadians diagnosed with a first cancer in childhood or adolescence. EClinicalMedicine, 16, pp.107-120.
