Abstract 10P
Background
Developing lymphoma as a second primary malignancy (SPM) after colorectal cancer is a very rare event reported in the literature, with an incidence of 0.5%. Very few studies reported an association of lymphoma with pre- and post-operative radiotherapy in colorectal cancer management. The potential risk of SPM, including lymphomas, is debatable in cancer management. So the aim of this study is to assess the risk of lymphoma as an SPM in colorectal cancer across different age groups.
Methods
Data were extracted using the Surveillance Epidemiology and End Result (SEER) database. We used an MP-SIR session with multiple outcome analysis to assess the risk of second primary lymphoma in colorectal cancer patients. SIR was calculated as observed/expected (O/E), and excess absolute risk (EAR) is per 10,000. Results were considered significant at P<0.05 with a 95% confidence interval (CI). We use the WHO age classification (0–24 young, 25–63 middle age, and older than 64 years).
Results
The risk of lymphoma as an SPM in colorectal cancer patients had an O/E of 0.93 (P<0.05, 95%CI: 0.89-0.97, EAR=-0.52) while in the 2–11 months interval the O/E was 1.19 (P<0.05,95%CI: 1.07-1.33, EAR=1.28). The risk of Nodal non-Hodgkin lymphoma had an overall O/E of 0.93 (P<0.05, 95%CI: 0.88-0.98, EAR=-0.34) while in the 2-11 months interval the O/E was 1.27 (P<0.05, EAR=1.140). The risk of lymphoma in the young age had an O/E 0.00 (95%CI: 0.00-4.14, P<0.05, EAR= -0.70) while the middle age had an overall O/E of 0.90 (P<0.05, 95%CI: 0.83-0.97, EAR=-0.47) with slight increased risk in the 2-11 months interval (O/E=1.12, P<0.05,). The risk of extranodal Hodgkin lymphoma had an O/E of 0.00 (P<0.05, EAR= -0.01). In the old age, the EAR was -0.57 for developing lymphoma (O/E=0.95, P<0.05) while in the 2–11 months interval had an O/E of 1.22 (P<0.05).
Conclusions
The results of this study show colorectal cancer patients have an increased risk of developing SPM lymphoma, especially in the 2–11-month interval. As early discovery will raise the chance of a successful outcome, we advise all middle-aged and older individuals with colorectal cancer to undergo routine follow-up starting from the time of diagnosis.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.