# Low Income Has a Negative Effect on Survival Following Diagnosis of Metastatic Colorectal Cancer—A Population‐Based Cohort Study

## TL;DR

People with low income diagnosed with advanced colorectal cancer have worse survival outcomes compared to those with higher income, despite overall improvements in treatment.

## Contribution

This study quantifies the persistent negative impact of low income on survival in metastatic colorectal cancer patients over time.

## Key findings

- One-year relative survival improved from 55% in 2007–2012 to 63% in 2017–2022.
- Low-income patients had significantly higher excess mortality compared to high-income patients (EMRR 0.84).
- The effect of income on survival remained consistent from 2007 to 2021.

## Abstract

Treatment for metastatic colorectal cancer (mCRC) has seen great advances but may not be equally available for all patients.

To evaluate the impact of socioeconomic status on cancer‐specific survival after diagnosis of mCRC, with emphasis on potential temporal trends in the effect of income.

This population‐based cohort study, based on 90,620 patients diagnosed with colorectal cancer in Sweden during 2007–2021 and registered in CRCBaSe, identified 33,498 patients with mCRC through 2022. We used relative survival to estimate excess mortality rate ratios (EMRRs) with 95% confidence intervals (CIs) comparing net survival by income quartiles, adjusting for sex, age, calendar year, education, marital status and birth country.

One‐year relative survival improved from 55% in 2007–2012 to 63% in 2017–2022. In the first years after the diagnosis of metastases there was an income gradient with the biggest contrast between high‐income and low‐income patients (EMRR (95% CI) at one year: 0.84 (0.81–0.88)). Year of mCRC diagnosis did not alter the effect of income on survival.

Despite significant improvements in cancer‐specific survival for mCRC over the last decades, socioeconomic disparities, particularly based on income, continue to affect survival outcomes. The impact of income remains consistent from 2007 to 2021.