Air pollution is a significant risk factor for serious health conditions that affect several critical body parts beyond the lungs. Recently, experts have highlighted that rising air pollution, including fine particulate matter (PM2.5) and ground-level ozone, has prompted calls for India-specific research into its potential contribution to cancer risk, particularly gastrointestinal (GI) cancers. "Cancer is a complex challenge that requires coordinated efforts across institutions, specialities and countries. By bringing experts together and encouraging the exchange of experience, we can create new opportunities to advance cancer research, improve early diagnosis and work towards better outcomes for patients," Dr D S Rana, Chairman, Trust Society, Sir Ganga Ram Hospital, said.

According to a PTI report, the issue was discussed at a two-day international conference on colorectal and other GI cancers organised by the Sir Ganga Ram Hospital in collaboration with the United Kingdom's The Christie NHS Foundation Trust.

"In our OPD, we are now seeing new GI cancer patients as young as 15 years old, which was uncommon five years ago. We must also pay attention to the environment in which people live," Dr Shyam Aggarwal, chairperson of the Department of Medical Oncology at the Sir Ganga Ram Hospital and the organising chairperson of the conference, said while highlighting the concern that cancer prevention could no longer be discussed only in terms of tobacco, diet and lifestyle.

The report has also mentioned that several emerging international studies have linked long-term exposure to air pollutants with higher cancer risk. However, researchers have cautioned that the findings establish associations and do not prove that pollution causes GI cancers directly or explains the reported rise in cases among younger patients.

Air pollution and GI cancer link

While air pollution is traditionally associated with respiratory illnesses and lung cancer, medical experts and researchers highlighted growing global evidence that toxic air affects the digestive tract:

  • Inhaled pollutants reach the gut: Fine particulate matter (PM2.5) and airborne toxins do not only remain in the lungs. When inhaled, micro-particles dissolve into the bloodstream or are cleared through the mucociliary escalator into the throat, where they are swallowed into the gastrointestinal system.
  • Systemic inflammation and ozone: Heavy air pollution, including ground-level ozone (O3) and PM2.5, causes systemic oxidative stress and inflammation, which can disrupt the gut microbiome and damage intestinal lining cells over time.

A study published in Epidemiologic Reviews this year, examining 70 studies on air pollution and gastrointestinal diseases, has found that long-term PM2.5 exposure is associated with higher mortality from GI cancers, particularly colorectal cancer.

Another study published in Nature Health this year has examined the cancer burden associated with ambient air pollution across 952 locations between 2000 and 2020. It has reported associations between increased exposure to PM2.5, nitrogen dioxide and ozone and a higher overall cancer risk.

However, the findings were not specific to GI cancers and did not establish direct causation.

The report flags a worrying trend of early-onset GI cancers in urban areas like Delhi. While toxic air pollution is a suspect environmental stressor being actively researched, doctors stress that it is one piece of a complex puzzle involving genetics, gut microbiota, and lifestyle factors. Early-onset GI cancers arise from a complex interplay of family history, genetic susceptibility, diet, lifestyle, gastrointestinal infections, and environmental exposures.

(with inputs from PTI)



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