Abstract
PurposeThe purpose of the study is to assess the global risk of extracolonic secondary primary cancers (SPCs) in patients with colorectal cancer (CRC).MethodsStudies of SPC in patients with CRC were included if they reported the standardised incidence ratio (SIR) for extracolonic SPCs in patients with CRC compared with the general population. Pooled summary estimates were calculated using a random-effects model.ResultsA total of 7,716,750 patients with CRC from 13 retrospective cohort studies that reported extracolonic SPC incidence were included. The overall risk of several SPCs was significantly higher in patients with CRC compared with the general population, including cancers of the urinary bladder (pooled SIR 1.19, 95% confidence interval (CI) 1.06–1.33; p = 0.003), female genital tract (1.88, 1.07–3.31; p = 0.03), kidney (1.50, 1.19–1.89; p = 0.0007), thorax (lung, bronchus and mediastinum) (1.16, 1.01–1.32; p = 0.03), small intestine (4.26, 2.58–7.01; p < 0.0001), stomach (1.22, 1.07–1.39; p = 0.003), and thyroid (1.40, 1.28–1.53; p < 0.0001), as well as melanoma (1.28, 1.01–1.62; p = 0.04). There was also a decreased risk of developing cancer of the gall bladder (0.75, 0.60–0.94; p = 0.01).ConclusionPatients with CRC had a significantly increased risk of extracolonic SPCs compared with the general population. These findings highlight the need to develop research strategies for the management of second primary cancer in patients with CRC.
Highlights
Colorectal cancer (CRC) is the fourth most common cancer type in the world and the third most deadly, accounting for about 10% of all incident cancers and cancer-related deaths each year [1, 2]
There has been an unexplained increase among young people [3,4,5,6,7]. This expanding population of CRC survivors faces long-term health concerns [8], such as the increased risk of developing second primary cancers (SPCs) [1, 9,10,11,12,13,14,15,16,17,18,19,20,21]. The reasons for this elevated risk remain unelucidated; various hypotheses have been posited in recent years, familial genetic predispositions such as Lynch syndrome [22, 23], similar tumorigenic epigenetic changes in response to environmental exposures, or carcinogens related to tissues originating from the same germ layer [17], as well as specific mutations common to CRC and certain second cancers [24]
Thirteen studies published between 1999 and 2021, including 7,716,750 patients (2.01 × 109 person-years) with CRC that reported extracolonic SPCs cancer incidence, were included in the metaanalysis according to our inclusion criteria [16, 18, 21, 27, 30,31,32,33,34,35,36,37,38]
Summary
Colorectal cancer (CRC) is the fourth most common cancer type in the world and the third most deadly, accounting for about 10% of all incident cancers and cancer-related deaths each year [1, 2]. This expanding population of CRC survivors faces long-term health concerns [8], such as the increased risk of developing second primary cancers (SPCs) [1, 9,10,11,12,13,14,15,16,17,18,19,20,21] The reasons for this elevated risk remain unelucidated; various hypotheses have been posited in recent years, familial genetic predispositions such as Lynch syndrome [22, 23], similar tumorigenic epigenetic changes in response to environmental exposures, or carcinogens related to tissues originating from the same germ layer [17], as well as specific mutations common to CRC and certain second cancers [24].
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