Colorectal cancer risk in association with colorectal cancer as a second malignancy in relatives: a nationwide cohort study

Table 1 Colorectal cancer risk among individuals who had a first-degree relative diagnosed with CRCa-1 or CRCa-2

Category		Family history of CRCa-1			Family history of CRCa-2			Comparison ^c (CRCa-1 vs. CRCa-2)
Category		N ^a	RR ^b	95%CI	N ^a	RR ^b	95%CI	P1	P2
Overall		2769	1.72	1.65–1.79	251	1.50	1.32–1.70	0.04	0.69
Gender	Among males	1551	1.76	1.67–1.86	143	1.54	1.31–1.83	0.14	0.74
Gender	Among females	1218	1.67	1.58–1.78	108	1.44	1.19–1.74	0.08	0.28
Age of CRC diagnosis in FDR	≤60 years old	536	2.11	1.94–2.30	19	2.16	1.38–3.38	0.93	0.21
Age of CRC diagnosis in FDR	> 60 years old	2233	1.64	1.57–1.72	232	1.46	1.28–1.66	0.08	0.23
Type of family history	Only parent	2147	1.68	1.60–1.75	204	1.51	1.31–1.73	0.15	0.97
Type of family history	Only sibling	622	1.89	1.74–2.05	47	1.45	1.09–1.93	0.08	0.52

CRC Colorectal cancer, CRCa-1 Colorectal cancer as a first primary malignancy, CRCa-2 Colorectal cancer as a second primary malignancy
^aN, number of CRC cases diagnosed during the follow-up
^bRR was estimated from Poisson regression using individuals without cancer family history as the reference. The covariates adjusted in the model included age groups (5 years), periods (5 years), socioeconomic status (blue-collar worker, white-collar worker, farmer, private business, professional, or other/unspecified) and place of residence (big cities, northern Sweden, southern Sweden and unspecific)
^ccomparison of familial risks associated with family history of CRCa-1 and CRCa-2 with Poisson regression. P1 is the p value for the comparison when the adjusted covariates were same as main analysis (above). P2 is the p value for the comparison when age at diagnosis of CRC in FDR (as continuous variable) and family relationship were additionally adjusted

ISSN: 1471-2407