Differences in outcome between right- and left-sided colon cancer: A population based study.

493 Background: Colon cancer is the second most frequent cause of cancer death, with an increasing incidence during the last decade. Recently, there is an increased interest in possible differences in outcome after surgery between right- and left-sided colon carcinoma (RCC and LCC). Methods: A population based study was performed in the south part of the Netherlands covering a region with more than 2 million inhabitants. Patients suffering from either RCC or LCC, excluding rectal cancer, were compared with regard to epidemiological, clinical and histological parameters as well as survival data. A Cox proportional hazard model was used to estimate the impact of different parameters on survival. Results: The data of 12,731 patients with colon cancer from January first 2000 and December 31 2010 were analyzed. Of these, 42% was RCC and 55% was LCC. In the remaining 3% of patients the location was not otherwise specified. In comparison with LCC, the majority of RCC patients were female (53% vs. 46%) and older (42% vs 34% > 75 years). The majority of RCC (77%) and LCC (87%) was non-mucinous adenocarcinoma. In RCC, 18% of tumors were mucinous adenocarcinoma vs 10% in LCC, p< 0.001. Well differentiated tumors were more common in LCC, 70% vs 58% in RCC Moderately and poorly differentiated tumors were more present in RCC compared to LCC (23% vs 13%, p<0.0001). Stage I tumors were more common for LCC vs stage II-IV tumors in RCC, p<0.0001. In RCC 1-9 lymph nodes were found in 37% vs 51% in LCC. In RCC 49% >10 LN were found vs 34% in LCC. No difference was found between anatomical sites regarding tumor positive LN, nor in LN ratio. Synchronous distant metastases were present in 30% of RCC vs 25% in LCC. Median overall survival in RCC was 46 months vs 60 months in LCC, p<0.0001. Survival differed between age groups and location and was worse for RCC with age 45-59 yrs: RCC vs LCC p<0.0008, age 60-74 yrs: RCC vs LCC, p<0.0006). Also, in T4 tumors, survival was worse for RCC, p<0.007. Conclusions: Prognosis of colon carcinoma is correlated to anatomical distribution with a significantly worse prognosis for RCC patients. Since RCC is more common in people of older age and the incidence is increasing, these findings may have future implications for the planning of treatment strategies.