Smoking May Drive Pancreatic Cancer Progression, Study Finds

A study from the University of Michigan’s Rogel Cancer Center revealed a previously unknown biological pathway explaining why smoking not only increases the risk of pancreatic cancer but also accelerates its progression. The findings, published in Cancer Discovery, illuminate how toxins from cigarettes trigger immune-mediated mechanisms that drive tumor growth and spread.¹

Person holding cigarette | Image Credit: © methaphum - stock.adobe.com

Pancreatic Cancer

Pancreatic cancer is notoriously aggressive, ranking among the deadliest cancers due to late diagnosis and poor response to therapy. Known risk factors include chronic pancreatitis, obesity, diabetes, family history, and especially smoking, which has long been associated with both increased incidence and poorer outcomes. However, the precise molecular basis by which smoking exacerbates disease progression has been largely misunderstood.^1,2

Smoking’s role in cancer development is well established, with tobacco-related carcinogens broadly implicated in various tumor types. For pancreatic cancer specifically, smoking has been linked to roughly 20% of cases, and heavy smokers face worse survival outcomes than non-smokers. This new study deepens clinical understanding by uncovering the immune system's role in amplifying the tumor-promoting effects of cigarette toxins.³

The Study

The researchers administered a chemical carcinogen commonly found in cigarette smoke to mice bearing pancreatic tumors, aiming to assess its effects on the immune landscape, particularly IL-22, a cytokine previously implicated in tumor microenvironments. In doing so, they discovered an immune mechanism that magnifies tumor aggression.^1,2

“It dramatically changed the way the tumors behave. They grew much bigger, they metastasized throughout the body. It was really quite dramatic,” Timothy L. Frankel, MD, co-director of the Rogel and Blondy Center for Pancreatic Cancer and Maud T. Lane Professor of Surgical Oncology at Michigan Medicine, and senior study author, said in a news release.²

Study Methods

The experimental approach involved treating tumor-bearing mice with a smoke-related chemical ligand. Researchers observed tumor behavior in both immunocompetent mice and those lacking functioning immune systems. This comparison revealed that the carcinogen’s effects hinged on immune activity. They then investigated immune cell populations and identified regulatory T cells (Tregs) that produce IL-22 and suppress anti-tumor immunity. Depletion of Tregs in mice neutralized the tumor-accelerating impact of the chemical. The team validated these findings using human immune cells and tissue samples from patients, comparing immune profiles of smokers versus non-smokers with pancreatic cancer.^1,2

Findings

The researchers discovered that a chemical carcinogen from cigarette smoke fueled rapid tumor growth and metastasis in mice—but only when the immune system was intact. A subset of regulatory T cells proved to be key drivers, simultaneously releasing IL-22 and suppressing anti-tumor immune responses. When these T cells were eliminated, the carcinogen’s tumor-promoting effects disappeared entirely.^1,2

“These T-regulatory cells have the ability to both make IL22 but also massively suppress any anti-tumor immunity. It’s a two-pronged attack. When we eliminated all the Treg cells from these mice, we reversed the entire ability of the cigarette chemical to let the tumor grow,” Frankel said.²

Human validation revealed that smokers with pancreatic cancer exhibited higher levels of these IL-22–producing Tregs compared with non-smokers. The team also demonstrated that a pharmacological inhibitor targeting the chemical’s signaling could shrink tumors—highlighting therapeutic potential.^1,2

“If we are able to inhibit the super suppressive cells, we might also unlock natural anti-tumor immunity,” Frankel explained. “This could be even further activated by current immunotherapies, which do not work well in pancreatic cancer because of the immunosuppressive environment.”²

Conclusion

This study offers compelling insight into how smoking amplifies pancreatic cancer risk and lethality through immune modulation. By identifying IL-22–producing T-regs as potent facilitators of tumor growth—especially in response to tobacco-related carcinogens—it opens avenues for targeted treatments and risk-tailored approaches. Inhibiting this pathway could not only slow disease progression but also enhance the efficacy of existing immunotherapies, which have so far struggled in pancreatic cancer due to its immunosuppressive environment.

“There’s a potential that we need to treat smokers who develop pancreatic cancer differently,” Frankel said. “We may also need to screen smokers more closely for pancreatic cancer development. There is not a great screening mechanism, but people who smoke should be educated about symptoms to look out for and consider referrals to a high-risk clinic.”²

REFERENCES

1. Griffith B, Kadiyala P, McGue J, et al. Aryl hydrocarbon receptor ligands drive pancreatic cancer initiation and progression through pro-tumorigenic T cell polarization. Cancer Discov. September 4, 2025. Doi:10.1158/2159-8290.CD-25-0377

2. Study shows how smoking drives pancreatic cancer. News Release. September 4, 2025. Accessed September 5, 2025. https://www.eurekalert.org/news-releases/1096775

3. Yuan C, Morales-Oyarvide V, Babic A, et al. Cigarette smoking and pancreatic cancer survival. J Clin Oncol. March 30, 2017. doi: 10.1200/JCO.2016.71.2026