Screening Associated With Overall Survival After Metachronous Metastasis in CRC

Longer overall survival (OS) was found to be independently associated with screen detection of the primary tumor in patients who had colorectal cancer (CRC) with diagnosed metachronous metastasis, according to a study published in the European Journal of Cancer.

Population screening programs for CRC throughout Europe have led to an increased number of cases being detected through screening, with the goal of reducing mortality. An estimated 20% of patients develop metachronous metastases if they are without metastasis at CRC diagnosis. This study aimed to establish if survival is affected by the detection of the primary tumor through screening.

Colorectal cancer awareness medical concept | Image credit: Dr_Microbe - stock.adobe.com

This retrospective, observational study used data from the Netherlands Cancer Registry (NCR). Patients considered for the study included those aged 18 years and older who were diagnosed with stage I to III CRC who developed metachronous metastases. Patients were excluded if they had an endoscopic resection rather than surgical for the primary tumor or if they opted for a wait-and-see approach to their rectal cancer after chemoradiation.

The NCR contained data on patients with CRC who had an incidence date of the primary tumor between January and June of 2015 and data on the development of metachronous metastasis between February and October of 2019 to be used for the study. Diagnosis of CRC was determined using the fecal immunochemical test (FIT). All patients who had done screening for CRC using FIT were recommended to do a colonoscopy if their results were positive; 79.4% of patients with a positive FIT followed up with a colonoscopy.

There were 794 adults who developed metachronous metastases after being diagnosed with stage I to III CRC between January and June of 2015. A total of 152 had a positive FIT that detected a CRC diagnosis, 19% of the study population. Patients were younger, more often had lower tumor stage, and had a favorable differentiation grade if they had a screen-detected tumor. The left side of the colon more often had screen-detected tumors whereas they were often limited to the liver at the first distant metastases diagnosis in screen-detected tumors.

Patients who had their tumors detected through screening received antitumor treatment for metastatic disease more frequently. Surgical resection of metastases was more common in patients with screen-detected primary tumors compared with patients with non-screen-detected primary tumors (41.4% vs 31.3% in the study population, 71.2% vs 55.9% in patients with liver-only metastatic disease).

The median OS was 22.3 (95% CI, 19.9-24.2) months for the total study population; the 1-year survival rate was 67.9% (95% CI, 64.7%-71.2%) and the 5-year survival rate was 22.0% (95% CI, 19.2%-25.2%). Patients with a screen-detected primary tumor had a median OS after metachronous metastasis that was longer compared with patients with a non-screen detected tumor (38.3 [95% CI, 29.4-46.5] vs 19.2 [17.3-21.9] months). The 1-year survival rate was higher in patients who had screen-detected primary tumors after metachronous metastasis compared with those who had non-screen-detected primary tumors (85.9% [95% CI, 79.4%-90.8%] vs 63.9% [95% CI, 60.3%-67.7%]); the same relationship was found for 5-year survival (35.4% [95% CI, 28.3%-44.3%] vs 18.8% [15.9%-22.3%]).

Screen detection was found to be associated with OS after metachronous metastasis (HR, 0.70; 95% CI, 0.56-0.89) after a multivariable analysis. A sensitivity analysis that excluded patients not aged 60 to 77 years found that the changes in median OS, 1-year survival rate, and 5-year survival rate were negligible when compared with the total population of the study but the association between screen-detection of the primary tumor after metastasis and overall survival was still significant (HR, 0.67; 95% CI, 0.52-0.86).

The researchers concluded that there was an independent association found between screen-detected primary tumors and longer OS after patients with CRC had metachronous metastases. This result emphasized the importance of continuing nationwide screening programs for CRC.

Reference

Hamers PAH, Vink GR, Elferink MAG, et al. Impact of colorectal cancer screening on survival after metachronous metastasis. Eur J Cancer. Published online November 12, 2023. doi:10.1016/j.ejca.2023.113429