Background: Little is known about colorectal cancer or colon and rectal cancer. Are they the same disease or different diseases?
Objectives: The aim of this epidemiology study was to compare the features of colon and rectal cancer by using recent national cancer surveillance data.
Design and setting: Data included colorectal cancer (1995-2008) from the Surveillance, Epidemiology, and End Results Program (SEER) database. Only adenocarcinoma was included for analysis.
Patients: A total of 372,130 patients with a median follow-up of 32 months were analyzed.
Main outcome measures: Mean survival of patients with the same stage of colon and rectal cancer was evaluated.
Results: Around 35% of patients had stage information. Among them, colon cancer patients had better survival than those with rectal cancer, by a margin of 4 months in stage IIB. In stage IIIC and stage IV, rectal cancer patients had better survival than colon cancer patients, by about 3 months. Stage IIB colorectal cancer patients had a poorer prognosis than those with stage IIIA and IIIB colorectal cancer. After adjustment of age, sex and race, colon cancer patients had better survival than rectal cancer of stage IIB, but in stage IIIC and IV, rectal cancer patients had better survival than colon cancer.
Limitations: The study is limited by its retrospective nature.
Conclusion: This was a population-based study. The prognosis of rectal cancer was not worse than that of colon cancer. Local advanced colorectal cancer had a poorer prognosis than local regional lymph node metastasis. Stage IIB might require more aggressive chemotherapy, and no less than that for stage III.