Table 1 Characteristics of included study of risk factors for metachronous colorectal cancer
First author’s last name [ref] | Year | Country | Study design | Total cohort population | Age at diagnosis | Sex | Follow-up time | Definition of outcome | Assessed risk factors | Confounders adjusted for in the analysis |
|---|---|---|---|---|---|---|---|---|---|---|
Yang [20] | 2018 | USA | Retrospective Cohort | 252,404 | Range < 40–80+ | 128,396 M + 124008F | 0 - > 8 years | CRC with a minimal interval of 6 months between the diagnoses was required to exclude synchronous cancer. | History of initial primary CRC, age at diagnosis, sex, race, SEER staging, if surgery, pathology grade | History of initial primary CRC, age at diagnosis, sex, race, SEER staging, if surgery, pathology grade |
Jayasekara [21] | 2016 | USA, Australia, Canada, New Zealand | Retrospective Cohort | 7863 | Mean 55.3 years | 3969 M + 3894F | Mean 6.6 years (range 1–16 years) | A metachronous CRC was defined as a new primary colon or rectal cancer diagnosed at least one year after the first diagnosis of primary colon or rectal cancer. | Age, sex, family history, synchronous CRC, synchronous adenoma, site, stage, grade, mismatch repair status, smoking, alcohol, body mass index, diabetes mellitus, aspirin, ibuprofen, multivitamin use, calcium intake, surveillance colonoscopy interval | Age, sex, family history, synchronous CRC, synchronous adenoma, site, stage, grade, mismatch repair status, smoking, alcohol, body mass index, diabetes mellitus, aspirin, ibuprofen, multivitamin use, calcium intake, surveillance colonoscopy interval |
le Clercq [22] | 2015 | Netherlands | Retrospective Cohort | 5157 | Mean 70.0 years | 2770 M + 2387F | Not given | A second primary colorectal adenocarcinoma diagnosed at least 6 months after the primary CRC diagnosis, and which was not a recurrence of the primary CRC. | Age, tumour size, appearance, differentiation | Age and sex |
Battersby [23] | 2014 | UK | Prospective Cohort | 538 | Median 70 years 11 months (IQR, 61 years 10 months–77 years 11 months) | 295 M + 243F | Median 4 years and 2 months (range 0–16 years) | Metachronous colorectal cancers are tumours that develop at a site remote from the primary tumour, which are histologically separate and occur 12 months or more after surgery, in a completely investigated colon. | Age | Competing events (death and recurrence), sex, stage, site, and number of polyps at initial colonoscopy |
Mulder [24] | 2012 | Netherlands | Retrospective Cohort | 10,283 | median 70.0 years | 5199 M + 5084F | 39,974 person-years | Pathologically proven CRC away from the previous line of anastomosis at least 6 months after the first diagnosis | Age, sex, TNM stage, synchronous CRC, time interval in between first and second diagnoses | Rate ratio of standardized incidence ratios standardized for age, sex, TNM stage, time interval in between first and second diagnoses |
Raj [25] | 2011 | USA | Retrospective Cohort | 104,257 | 65.6 years ±10.9 (SD) for colon cancer and 62.8 years ±11.5 (SD) for rectal cancer | 56,705 M + 47552F | 618,104 person-years | Second CRC was diagnosed more than 6 months of the first diagnosis | Sex, ethnicity | Adjusted for age |
Park [15] | 2006 | Korea | Retrospective Cohort | 5447 | Mean 55 years | 3208 M + 2239F | Not given | A metachronous cancer was defined as a second primary colorectal cancer occurring more than 6 months after the index cancer without evidence of local recurrence or metastasis from the primary tumour | Age (≤40 years), sex, family history of CRC and related cancer, location of index cancer, differentiation, existence of synchronous polyps or cancer | Age, sex, family history of CRC and related cancer, location of index cancer, differentiation, existence of synchronous polyps or cancer |
Das [26] | 2006 | USA | Retrospective Cohort | 216,751 | 50 years or more | M + F | 1,250,687 person years | Either in situ or malignant and microscopically confirmed and diagnosed subsequent to the index CRC more than 6 months | Age, sex, site, stage of first primary, time period of diagnosis of first primary (1973–1977 vs 1988–1992) | Age, sex, site, stage of first primary, time period of diagnosis of first primary (1973–1977 vs 1988–1992) |
Yamazaki [27] | 1997 | Japan | Retrospective Cohort | 284 | Mean 59.5 years | 174 M + 110F | Mean 53 months | Neoplastic findings after the first six-month surveillance | Age, sex, tumour stage, tumour site, tumour grade, depth of invasion, lymph node metastasis, carcinoma in other organs, familial history of colorectal carcinoma, synchronous adenoma or carcinoma | Age, sex, tumour stage, tumour site, tumour grade, depth of invasion, lymph node metastasis, carcinoma in other organs, familial history of colorectal carcinoma, synchronous adenoma or carcinoma |
Bouvier [4] | 2008 | France | Retrospective Cohort | 10,801 | Median 71.1 years | 5998 M + 4803F | 61,879 person years | A new colorectal cancer occurring at least 6 months after the initial colorectal cancer | Sex, size, growth features, stage of first cancer, synchronous CRC, associated adenomas or adenoma remnants | Sex, size, growth features, stage of first cancer, synchronous CRC, associated adenomas or adenoma remnants |
Gervaz [28] | 2005 | Switzerland | Retrospective Cohort | 5006 | Range 20–85+ | M + F | Not given | A pathologically proved adenocarcinoma that distinctly separated from the previous line of anastomosis and diagnosed at a minimal interval of 6 months after the initial carcinoma. The possibility that the second lesion represents a recurrence must be ruled out beyond reasonable doubt | Location of the index cancer | Not mentioned |
Shitoh [29] | 2002 | Japan | Retrospective Cohort | 272 | Not given | M + F | Median 75 months | CRC more than 1 year after the first primary CRC | Coexistent adenoma, family history of CRC, past history of extracolonic malignancy (all malignant neoplasms were included), MSI status | Coexistent adenoma, family history of CRC, past history of extracolonic malignancy (all malignant neoplasms were included), MSI status |
Togashi [30] | 2000 | Japan | Retrospective Cohort | 341 | Mean 59.6 years | 209 M + 132F | Mean 6.2 years | All CRCs detected in surveillance colonoscopy which occurred more than 6 months after the surgery | Concurrent adenoma, synchronous CRC, extracolonic malignancy, family history of CRC in first degree relative | Concurrent adenoma; synchronous CRC; extracolonic malignancy; family history of CRC in first degree relative |