Dermatologists in Finland Confirm the Association between Cigarettes and Squamous Cell Skin Cancer

There’s another reason to put down the cigarettes. A study published in May 2024 confirmed a connection between smoking tobacco and nonmelanoma skin cancer.

Finnish dermatologists recruited 488 participants at the Kuopio University Hospital in Kuopio, Finland, to assess whether there was any evidence between smoking and skin cancer. They found there was, but not in the way they expected.

Results determined an increased risk for squamous cell skin cancer (also-squamous cell carcinoma) among smokers, but no association with basal cell carcinoma or melanoma. Previous studies that were negative for an association between tobacco smoking and nonmelanoma skin cancer incidence enrolled large proportions of participants with basal cell carcinoma, but very few with squamous.

This study strived to enroll more patients with squamous cell skin cancer. It included 286 individuals with past or present skin cancers. Among those, 100 had a diagnosis of melanoma, 202 had a diagnosis of basal cell carcinoma, and 38 had a diagnosis of squamous cell skin cancer.

Although smoking tobacco is a known carcinogenic initiator of many cancer types, previous studies on nonmelanoma skin cancer were uncertain about the connection. The Finnish study defined tobacco smoking as combustible tobacco contained in cigarettes, pipes, and cigars.

Surprisingly, there was no association between the tobacco amount or number of years as a smoker and squamous cell skin cancer. The data showed a significant association between smoking less than ten tobacco pack-years and squamous cell skin cancer, but not more than ten tobacco pack-years. Although this result appears confusing or contradictory, a previous analysis supported the connection.

In 2017, an international study on the risks of cigarette smoking with nonmelanoma skin cancer demonstrated that current smokers had significantly higher risks of squamous cell skin cancer. They also found no trend between the duration of smoking and cancer. The number of individuals included was 43,794 adult men and women, ages 40 to 69 years, sampled randomly from the population of Queensland, Australia, in 2011.

Both studies used samples of populations at high risk for nonmelanoma skin cancers and found an association between smoking and squamous cell skin cancer. The outstanding question is why squamous cell but not basal cell carcinoma, actinic keratoses, or melanoma. Studies have shown that chronic exposure to UV and cigarette smoke alters the skin’s texture, including advancing the signs of aging, but this is only part of the answer.

Researchers in both studies suggested an explanation for their findings. The Finnish researchers indicated that nicotine may suppress skin inflammation, which would inadvertently increase the risk of skin cancer in the presence of damage to the skin. Australian and British researchers also suggested that nicotine would suppress the immune system. Still they could not account for why this would only impact squamous cells and not basal cells. Further studies could focus on understanding why this occurs.

This summary is based on these publications:

Uotila I, Siiskonen H, Haimakainen S et al. Tobacco smoking is associated with cutaneous squamous cell carcinoma but not with basal cell carcinoma or melanoma in adult subjects at risk of skin cancer: A cross-sectional study. Tob Induc Dis. 2024:22.

Dusingize JC, Olsen CM, Pandeya NP et al. Cigarette Smoking and the Risks of Basal Cell Carcinoma and Squamous Cell Carcinoma. J Invest Dermatol. 2017;137(8):1700-1708.