Q: Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Context: Rectal cancer has a higher risk of developing lung metastasis compared with colon cancer. It is unclear whether the prognosis after pulmonary metastasectomy for these distinct tumors is different.', 'Patients who underwent pulmonary metastasectomy for colorectal carcinoma were analyzed for survival and patterns of recurrence depending on the location of the primary colorectal cancer. Multivariate regression analysis was performed to identify clinical variables predictive of survival after pulmonary metastasectomy.', 'Between 1985 and 2012, 698 patients underwent pulmonary metastasectomy for metastatic colorectal cancer. Complete information was available in 626 patients. These patients were divided into groups based on whether the primary tumor was colon or rectal in origin. Median follow-up was 45.5 months (range, 23 to 287 months). There were no statistical differences between the two groups in terms of number of lung metastases, tumor size, or lymph node involvement. There was no difference in overall survival (p= 0.545). Five-year disease-free survival for colon cancer patients was 67.2% compared with 60.1% for rectal cancer (p= 0.004). The most common sites of recurrence after pulmonary metastasectomy were liver in colon cancer and lung in rectal cancer. Multivariate Cox proportional hazards analysis indicated that rectal cancer (hazard ratio, 1.39; 95% confidence interval, 1.07 to 1.83; p= 0.015) and multiple metastases (>3; hazard ratio, 1.41; 95% confidence interval, 1.04 to 1.89; p= 0.027) were independent adverse risk factors affecting disease-free survival after pulmonary metastasectomy.
Answer: Disease-free survival and site of recurrence after pulmonary metastasectomy for colorectal carcinoma are dependent on the site of the primary tumor. Lung metastases from rectal cancer have a worse disease-free survival compared with colon cancer. This may influence treatment and follow-up strategies.
A:
Does the prognosis of pulmonary metastasectomy depend on the location of the primary colorectal cancer?