The effects of chemotherapy, primary tumor location and histological subtype on the survival of stage III colon cancer patients

Abstract

Objective: Colon cancer (CC) is one of the most common cancers worldwide and has a poor prognosis. Surgery followed by adjuvant chemotherapy is the standard treatment strategy for stage III CC patients. Primary tumor location (PTL) is an important factor for the long-term survival of CC. However, the difference in the prognosis between the histological subtypes of mucinous adenocarcinoma (MAC) and nonspecific adenocarcinoma (AC) in stage III CC patients is unclear. The correlation of chemotherapy, PTL and histological subtype with the overall survival (OS) of stage III CC patients has not yet been explored.

Methods: Patients diagnosed with stage III CC from 2010 to 2016 in the Surveillance, Epidemiology, and End Results (SEER) database were retrieved. The clinicopathological features and OS were analyzed according to the chemotherapy, PTL and histological subtype.

Results: A total of 28,765 eligible stage III CC patients were enrolled in this study. The results showed that chemotherapy, left-sided CC (LCC) and AC were favorable prognostic factors for OS. Right-sided CC (RCC) had worse OS than LCC regardless of chemotherapy. MAC had worse OS than AC in the patients with chemotherapy, but the survival benefits disappeared in the patients without chemotherapy. Additionally, in LCC, MAC had worse OS than AC regardless of chemotherapy. However, in RCC, MAC had worse OS than AC in patients with chemotherapy but had similar OS to AC in patients without chemotherapy. In the AC group, RCC had worse OS than LCC regardless of chemotherapy. In the MAC group, RCC had comparable OS to LCC regardless of chemotherapy. Four subgroups, i.e., RCC/MAC, RCC/AC, LCC/MAC and LCC/AC, all showed benefits from chemotherapy. Among them, LCC/AC had the best OS, and RCC/MAC had the worst OS compared with the other three subgroups.

Conclusion: The prognosis of MAC is worse than that of AC in stage III CC. LCC/AC has the best OS, while RCC/MAC has the worst OS but still benefits from chemotherapy. The impact of chemotherapy on survival is greater than that of histological subtype, but the impact of histological subtype on survival is similar to that of PTL.

Keywords: Chemotherapy; Colon cancer; Mucinous adenocarcinoma; Overall survival; Primary tumor location.

Fig. 1

Flowchart of patient inclusion and exclusion into the study. SEER, Surveillance, Epidemiology, and End Results; AJCC, American Joint Committee on Cancer; RCC, right-sided colon cancer; LCC, left-sided colon cancer; AC, nonspecific adenocarcinoma; MAC, mucinous adenocarcinoma

Fig. 2

Long-term survival of patients with stage III CC according to chemotherapy, PTL and histology. A The survival curves showed that the OS of the nonchemotherapy patients was poorer than that of the chemotherapy patients. B The survival curves showed that the OS of RCC patients was poorer than that of LCC patients. C The survival curves showed that the OS of MAC patients was poorer than that of AC patients

Fig. 3

The impact of PTL and histological subtype on the survival of patients with stage III CC stratified by chemotherapy. A For nonchemotherapy patients, LCC had better OS than RCC. B For chemotherapy patients, LCC had better OS than RCC. C For nonchemotherapy patients, AC patients had comparable OS with MAC patients. D For chemotherapy patients, AC patients had better OS than MAC patients with chemotherapy

Fig. 4

The impact of the interplay of PTL and histological subtype on long-term survival of stage III CC patients with chemotherapy. A The stratified analysis survival curves showed that AC had a better OS than MAC in the RCC group. B The stratified analysis survival curves showed that AC had a better OS than MAC in the LCC group. C The stratified analysis survival curves showed that LCC had a better OS than RCC in the AC group. D The stratified analysis survival curves showed that LCC had comparable OS with RCC in the MAC group

Fig. 5

The long-term survival difference between the four subgroups, RCC/MAC, RCC/AC, LCC/MAC and LCC/AC. A The survival curves showed that LCC/AC had the best OS compared with the other three subgroups, which had similar OS. B For patients without chemotherapy, LCC/AC had the best OS compared with the other three subgroups, which had similar OS. C For patients with chemotherapy, LCC/AC had the best OS, followed by RCC/AC and LCC/MAC, which had similar OS, and RCC/MAC, which had the worst OS. D The results showed statistical analysis for Figures A, B and C. E The results showed that patients with chemotherapy had a better OS than those without chemotherapy in the RCC/MAC, RCC/AC, LCC/MAC, and LCC/AC groups

Fig. 6

The impact of the interplay of PTL and histological subtype on the long-term survival of stage III CC patients without chemotherapy. A The stratified analysis survival curves showed that AC had comparable OS with MAC in the RCC group. B The stratified analysis survival curves showed that AC had a better OS than MAC in the LCC group. C The stratified analysis survival curves showed that LCC had a better OS than RCC in the AC group. D The stratified analysis survival curves showed that LCC had comparable OS to RCC in the MAC group

Fig. 7

Risk factors for long-term survival of stage III CC patients. Multivariate analysis of factors associated with OS in stage III CC patients