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Songtanin et al. | Journal of Clinical and Translational Research 2023; 9(5): 308-316 311

Figure 2. Forest plot of appendectomy in patients with colon cancer in comparison to control patients.

Figure 3. Forest plot of appendectomy in proximal colon cancer in comparison to distal colon cancer.

Figure 4. Forest plot of appendectomy in patients with colon cancer in comparison to patients with rectal cancer.

3.4. Quality assessment 20-year follow-up period, the incidence of colorectal cancer
was 73.1/100,000 person-years in the appendectomy group and
During the article screening, there was good agreement 39.7/100,000 person-years in the control group. The overall risk
between the two authors as demonstrated by a Newcastle-Ottawa of the development of colorectal cancer was increased by 73% in
score, shown in Tables S2 and S3. Funnel plots were constructed appendectomy cases, and these cases had significantly higher risk
to assess the risk of publication bias across series for all outcome for the development of cancer in the proximal colon than in the
measures. distal colon and rectum.
4. Discussion This meta-analysis included 384,297 appendectomies and
39,711 colon cancer cases and demonstrated that appendectomy
In this study, patients with distal colon and rectal cancer has a significant association with proximal colon cancer
were compared to patients with proximal colon cancer because (OR = 1.48 [95% CI: 1.29, 1.69], P < 0.0001) with low
the cancers in these two locations have different clinical and heterogeneity between studies. In the analysis which compared
genetic/molecular features. The prevalence of proximal colon the frequency of appendectomy in all patients with colon cancer
cancer (40.4%) is higher than distal colon cancer (28.9%) and with the frequency of appendectomy in healthy controls, the
rectal cancer (30.7%) [25]. A study based on the SEER database association was not significant but did become significant when
reported that proximal colon has a worse prognosis compared the Lee J study was excluded [19]. This might be explained by
than distal colon cancers, but the reason remains unclear [26]. the effect of a lag period from appendectomy to the diagnosis of
Shi et al. reported a longitudinal study of 43,976 appendectomy colorectal cancer. Lee J reported a positive association with no
cases and 85,179 age- and gender-matched non-appendectomy lag period (HR = 1.44 [95% CI: 1.14, 1.83]) but no association
controls and the development of colon cancer [27]. During the with a 3-year lag period (HR = 0.75 [95% CI: 0.50, 1.13]). Lai
DOI: http://dx.doi.org/10.18053/jctres.09.202305.23-00090