Second primary cancer in patients with colorectal cancer after a curative resection.
BACKGROUND
Colorectal cancer (CRC) patients have an increased risk of developing other malignancies. Understanding the characteristics of the second primary cancer is important to establish an effective surveillance program.


METHODS
This study investigated 301 CRC patients to assess the risk factors for postoperative primary cancers arising from organs distinct from the colorectal area (extracolorectal cancers). The observed/expected ratio (O/E ratio) was calculated using the Osaka Cancer Registry, to determine the rate of increase in extracolorectal cancers.


RESULTS
The frequency of postoperative extracolorectal cancers was 12.6%. A logistic regression analysis showed only age to be an independent risk factor for postoperative extracolorectal cancer development. The O/E ratio of overall postoperative extracolorectal cancer was significantly higher than one (O/E ratio 2.6, p < 0.01). In each organ, the frequency of lung and gastric cancers were significantly higher than one, with O/E ratios of 3.2 and 2.7 (p < 0.01 and p < 0.05, respectively).


CONCLUSIONS
The frequency of postoperative extracolorectal cancers in CRC patients was significantly higher than that in the normal population, especially for lung and gastric cancers. Clinicians should carefully follow patients for a possible recurrence of CRC and educate CRC patients with regard to the high risk of a second primary cancer.
Noura
Shingo
S
Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan. noura-si @ mc.pref.osaka.jp
Ohue
Masayuki
M
Seki
Yosuke
Y
Tanaka
Koji
K
Motoori
Masaaki
M
Kishi
Kentaro
K
Miyashiro
Isao
I
Ohigashi
Hiroaki
H
Yano
Masahiko
M
Ishikawa
Osamu
O
Tsukuma
Hideaki
H
Murata
Kohei
K
Kameyama
Masao
M
D000230:Adenocarcinoma / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003082:Colectomy / Q000379:methods*; D015179:Colorectal Neoplasms / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000473:pathology; D012042:Registries; D012307:Risk Factors