Incidence of late recurrence and second primary cancers 5–10 years after non‐metastatic colorectal cancer

Abstract

The fraction of patients who are cancer‐free survivors 5 years after curative‐intended surgery for colorectal cancer (CRC) is increasing, suggesting that extending surveillance beyond 5 years may be indicated. Here we estimate the incidence of late recurrence, metachronous CRC, and second primary cancers 5–10 years postoperative. All patients resected for UICC stage I–III CRC in Denmark through 2004–2013 were identified. Through individual‐level linkage of nationwide health registry data, recurrence status was determined using a validated algorithm. Cancer‐free survivors 5 years after surgery, were included. Cumulative incidence functions (CIF) of late recurrence, metachronous CRC, and second primary cancer 5–10 years postoperative were constructed. Subdistribution hazards ratios (sHR) were computed using Fine‐Gray regression. Among 8883 patients, 370 developed late recurrence (5–10‐year CIF = 4.1%, 95%CI: 3.7%–4.6%), 270 metachronous CRC (5–10‐year CIF = 3.0%, 95%CI: 2.7%–3.4%), and 635 a second primary cancer (5–10‐year CIF = 7.2%, 95%CI: 6.7%–7.7%). The risk of late recurrence was reduced for patients operated in 2009–2013 compared to 2004–2008 (2.9% vs. 5.6%, sHR = 0.52, 95% CI: 0.42–0.65). The risk of metachronous CRC was likewise reduced from 4.1% to 2.1% (sHR = 0.50, 95%CI: 0.39–0.65). While the risk of second primary cancer did not change between 2009–2013 and 2004–2008 (7.1% vs. 7.1%, sHR = 0.98, 95% CI: 0.84–1.15). Using nation‐wide 10‐year follow‐up data, we document that the incidences of late recurrence and metachronous CRC are low and decreasing from 2004 to 2013. Thus, despite increasing numbers of long‐term cancer survivors, the data do not advocate for extending CRC‐specific surveillance beyond 5 years.