Appendicitis as an early manifestation of subsequent malignancy: an asian population study.
OBJECTIVE
Cancer risk after appendectomy in patients with appendicitis remains unclear. This study examined the role of appendicitis as an early manifestation harbingering the distant malignancy.


METHODS
From the insurance claims data of Taiwan, we identified a cohort of 130,374 patients newly received appendectomy from 2000-2009, without cancer diagnosis. A comparison cohort of 260,746 persons without appendectomy and cancer was selected from the same database, frequency matched by age, sex, comorbidity and index year. We monitored subsequent cancers with a12-month follow-up.


RESULTS
Over all, 1406 and 616 cancer cases were identified in the appendectomy cohort and comparisons, respectively, with all cancers incidence rate 4.64-fold higher in the appendectomy cohort (9.06 vs. 1.96 per 1000 person-months). Digestive and female genital organs harbored 80.9% of cancer cases in the appendectomy cohort. The Cox model measured site-specific hazard ratio (HR) was the highest for female genital cancers (23.3), followed by cancers of colorectum (14.7), small intestine (10.1), pancreas (7.40), lymphoma (5.89) and urinary system (4.50), all significant at 0.001 level. The HR of all cancers decreased from 13.7 within 3 months after appendectomy to 1.37 in 7-12 months after the surgery. In general, relative to the comparison cohort, younger appendectomy patients tended to have a higher HR than older patients.


CONCLUSIONS
The high incident cancers identified soon after appendectomy suggest the acute appendicitis is the early sign of distant metastatic malignancy. The risk of colorectal cancer, female genital cancer and haemopoietic malignancy deserve attention.
Trauma and Emergency Center, China Medical University Hospital, Taichung 404, Taiwan; College of Medicine, China Medical University, Taichung 404, Taiwan.
Shih-Chi
SC
Wu
College of Medicine, China Medical University, Taichung 404, Taiwan; Division of Colorectal Surgery, Department of Surgery, China Medical University Hospital, Taichung 404, Taiwan.
William Tzu-Liang
WT
Chen
College of Medicine, China Medical University, Taichung 404, Taiwan; Management Office for Health Data, China Medical University and Hospital, Taichung 404, Taiwan.
Chih-Hsin
CH
Muo
Management Office for Health Data, China Medical University and Hospital, Taichung 404, Taiwan; Institute of Clinical Medical Science, China Medical University College of Medicine, Taichung 404, Taiwan.
Fung-Chang
FC
Sung
D000368:Aged; D001062:Appendectomy / Q000379:methods; D001064:Appendicitis / Q000150:complications* / Q000601:surgery; D044466:Asian People; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan