br Colorectal cancer survival at an oncologic center in

Colorectal cancer survival at an oncologic center in Colombia. A historic cohort 179
Table 2 Histopathologic, laboratory, clinical and treatment characteristics.
Characteristics Colon Rectum Total
Histologic type
a Squamous cell carcinoma, melanoma, sarcoma, neuroendocrine cancer, PEComa. b A person could have had more than one metastasis site and more than one second primary site.
c Reproductive system, central nervous system, soft tissues, pleura, bladder, kidney, pancreas, abdominal wall, mediastinum, skin, amygdala, small bowel.
Figure 3 Overall survival by stage in colon cancer (a) and rectal cancer (b).
Figure 4 Disease-free survival by cancer type.
The mean age of our study patients at diagnosis (63.3 years) corresponded to that of the majority of patients in other parts of Colombia and the world.3,6-9,18,19 Contrary to that reported in the majority of studies from devel-oped countries, in which incidence is higher in men,3,20,21 we observed a predominance in women, which has been 
Figure 5 Disease-free survival by stage in colon cancer (a) and rectal cancer (b).
described in other national studies.7-9 The hypotheses for predominance in men have been their greater exposure to risk factors and female Acetylcysteine as protective factors in women.
The most important risk factors in our study were smoking and alcohol consumption. They have consistently been described as carcinogens associated with numerous neoplasias,22 including colorectal cancer. Their frequencies vary among the different studies, but they are more consis-tent in relation to smoking, which has reached 52% in some reports.6,7,9,23 Another relevant risk factor we found was dia-betes mellitus, which concurs with the data from different analyses worldwide that have also reported a higher mortal-ity rate in those patients.6,24-26 Despite the clear association biochemistry has been shown between a family history of colon can-cer and the incidence of colorectal cancer and a 2 times increased risk, or higher, for colorectal cancer if at least one first-degree relative presents with the disease, a fam-ily history of colon cancer was infrequent in our study, as well as in others.6,7,20,23,27 Most of our patients were normal weight, followed by overweight, and a smaller percentage were obese, which is congruent with findings from other Colombian studies.8,9,23 Obesity has been identified as a risk
Colorectal cancer survival at an oncologic center in Colombia. A historic cohort 181
Figure 6 Overall survival by stage in the right colon (a) and the left colon (b).
factor 28-30 and should be taken into account in Colombia, given its increasing prevalence.
The main symptoms in our patients were rectal bleed-ing and abdominal pain, results that are similar to those reported in the national and international literature, in which positive predictive values reached 12.9 and 13.5, respectively, in some meta-analyses.31,32 The main symp-toms in our patients were followed by changes in bowel habit, diarrhea, constipation, weight loss, and anemia, find-ings that also concur with those of other studies.6-8,23 Only 0.8% of patients were asymptomatic at diagnosis, suggesting that educating patients to recognize disease symptoms could impact their outcomes. Initial presentation as obstruction or perforation, with a reported frequency of 3 to 40% in the lit-erature, more common in the colon than in the rectum (21.7 and 5.9%, respectively) and with a higher mortality rate, was not found in our study.33,34
The most frequent stage at diagnosis was stage iii, fol-lowed by stage ii and stage iv.Percentages were similar for stages ii and iv and very few patients presented with in situ tumors. Almost all the tumors (98.1%) were adenocarcino-mas, nearly half of which were well-differentiated. Close to half of the tumors were located in the rectum, almost