Prognostic Significance May Exist for CRC Tumor Sites

Location of a colorectal cancer (CRC) tumor could have implications on prognosis in recurrence-free survival (RFS) as well as survival after recurrence, according to a study published in Japanese Journal of Clinical Oncology. The 3 tumor sites studied were particularly relevant in preoperative CRC.

The prognostic value of the primary tumor location for CRC has been studied in the past, as the right and left colon differ in their microbiota. Unresectable CRC has used sidedness as a prognostic indicator for the efficacy of chemotherapy, but the relationship between sidedness and resectable CRC has not been studied as thoroughly. This study aimed to assess what relationship exists between primary tumor location in patients with stage I-III CRC and prognostic factors, specifically in those who had resection without prior treatment.

Colorectal cancer | Image credit: appledesign - stock.adobe.com

Patients who had curative surgery for stage I-III CRC between January 2000 and December 2015 were included in this study. All patients had a recommended follow-up of 5 years after their surgery, which lasted through January 31, 2021. Patients were excluded if they had multiple tumors, multiple CRCs, unknown follow-up information, histology other than adenocarcinoma, unknown stage information, or preoperative adjuvant therapy.

Follow-ups in this cohort included a physical exam and measurements of serum carcinoembryonic antigen and CA19-9 measurements every 3 months in the first 2 years and every 6 months for the following 3 years, CT scans every 6 months for 5 years, and colonoscopy at 1 and 3 years.

Follow-up data were analyzed until either an event occurred or the end of the follow-up period. All patients were divided into a right-sided colon group, left-sided colon group, and a rectum group based on the location of their tumor. Overall survival (OS) and RFS were evaluated separately.

There were 3770 patients included in the study who had curative surgery for stage I-III CRC, of which 15.9% had recurrence. Patients with stage I left-sided colon cancer (LCC) had a 3-year OS of 99.0% and a 5-year OS of 98.2% compared with those with right sided colon cancer (RCC), who had OS rates of 98.4% and 97.3%, respectively; patients with stage I rectal cancer (RC) had OS of 98.5% and 97.2% for 3- and 5-year follow-ups. The OS progressively decreased in each type of CRC, with stage III LCC having 3- and 5-year OS rates of 92.7% and 88.7%, respectively; stage III RCC having 89.3% and 83.0% OS; and stage III RC having 89.9% and 80.2% OS.

RFS rates for stage I LCC were 96.6% and 95.1% for 3- and 5-year follow-ups, respectively, compared with 96.9% and 94.5% for stage I RCC and 94.9% and 90.6% for stage I RC. The stage III rates for 3- and 5-year follow-up were worse for all 3 types, with LCC having 77.0% and 75.3% RFS, RCC having 77.8% and 75.3%, and RC, 65.9% and 59.8%.

Recurrent RCC of stage I-III had the worst survival after recurrence compared with LCC and RC, with 3- and 5-year survival rates being 48.6% and 35.0% vs 68.5% and 49.7% in LCC and 60.3% and 44.5% in RC. Poor RFS after recurrence was associated with age, sex, adjuvant therapy, and tumor location. A poor OS was associated with age (HR, 1.72; 95% CI, 1.37-2.15; P < .001), sex (HR, 0.73; 95% CI, 0.62-0.87; P < .001), adjuvant therapy (HR, 1.11; 95% CI, 0.91-1.36; P < .001), and tumor location, among other factors, according to a multivariable analysis.

RCC was significantly associated with better RFS compared with LCC (HR, 1.29; 95% CI, 1.03-1.63) and RC (HR, 1.89; 95% CI, 1.51-2.38). However RCC was also associated with poor survival after recurrence compared with LCC (HR, 0.68; 95% CI, 0.48-0.97) and RC (HR, 0.79; 95% CI, 0.57-1.10).

There were some limitations to this study. Treatment for CRC changed over the course of the study period, which lasted more than 20 years, and the presence or absence of these new treatments could have affected the treatment outcomes. Also, postoperative chemotherapy was only given to 23% of the patients, and genetic information was not available. This study also was conducted in a single center in Japan, which could limit generalizability.

Prognostic differences were found in patients with RCC, LCC, and RC when it came to recurrence and OS. Addressing RCC, LCC, and RC as separate entities could help to indicate prognostic biomarkers in stage I-III CRC, the study investigators concluded.

Reference

Inoue M, Kanemitsu Y, Tsukamoto S, Moritani K, Takamizawa Y, Daiko H. Prognostic impact of primary tumour location after curative resection in stage I-III colorectal cancer: a single-centre retrospective study. Jpn J Clin Oncol. Published online March 26, 2024. doi:10.1093/jjco/hyae035