Study Associates Smoking with Decreased Cancer Screening Rates, Advanced Stage Disease at Diagnosis

A study published in BMJ Open indicated that active smoking in women is strongly associated with a decrease in use of cancer screening services as well as more advanced cancer stage at the time of diagnosis.

Given these findings, researchers suggested that clinicians should emphasize the importance of both smoking cessation and cancer screening for this high-risk group.

“Patients of all smoking histories should be encouraged to receive regular mammograms and [faecal occult blood test; FOBT]/endoscopy, particularly active smokers who are less likely to seek screening,” the authors wrote. “Public health initiatives should continue the effort of encouraging smoking cessation to minimize smoking-related morbidities."

In this prospective, population-based cohort study, researchers evaluated the questionnaire responses of 89,058 postmenopausal women who participated in the Women’s Health Initiative (WHI) Observational Study. Of this cohort, 52.8% were never smokers, 40.8% were former smokers, and 6.37% were current smokers.

With an average of 8.8 years of follow-up, current smokers were found to have lower odds of obtaining breast (OR, 0.55; 95% CI, 0.51-0.59), cervical (OR, 0.53; 95% CI 0.47-0.59), and colorectal cancer (OR, 0.71; 95% CI 0.66, 0.76) screening compared with never smokers. Further, former smokers were more likely than never smokers to receive regular screening services.

“Concern for personal health is the most common reason given for smoking cessation among former smokers and may explain why this health-conscious population seeks cancer screening more frequently than never smokers,” the authors wrote. “On the contrary, smokers are overly optimistic about their health and consistently underestimate the magnitude of their cancer risk.”

“This dichotomy in risk perception corresponds with our results, indicating that current smokers have the lowest rates of screening while former smokers approach and often exceed never smokers in cancer screening, which could correspond to an overall advantage in seeking other preventive health behaviors,” the authors continued.

Altogether, failure to adhere to screening guidelines led to diagnoses at higher cancer stages among current smokers for both breast cancer (OR 2.78; 95%CI 1.64 to 4.70) and colorectal cancer (OR 2.26; 95%CI 1.01 to 5.05).

“The role of cigarette smoking in the etiology of breast cancer remains unclear—perhaps a higher risk of breast cancer could be due to less screening in addition to the genotoxic damage from smoke,” the authors noted. “Nonetheless, active smokers without recent testing fare the worst in cancer staging and deserve targeted attention to ensure timely cancer screening.”

Importantly, this study was purely observational and focused on postmenopausal women. Moreover, self-reported data on smoking and cancer screening may be subject to recall bias and social desirability bias.

In addition, current guidelines for colorectal cancer screening recommend annual FOBT and endoscopy every 5 years, though colorectal cancer screening was only recorded in the study dataset by having had either a FOBT or an endoscopy within the past 5 years. Therefore, researchers were not able to provide a separate analysis with shorter time intervals using annual FOBT results.

Reference:

Eng VA, David SP, Li S, Ally MS, Stefanick M, Tang JY. The association between cigarette smoking, cancer screening, and cancer stage: a prospective study of the women’s health initiative observational cohort. BMJ Open. doi: 10.1136/bmjopen-2020-037945