LONDON – One-third of current smokers with head and neck cancer experienced substantial difficulties in swallowing 1 year after radiotherapy, according to the results of a Danish study.
In comparison, 20% of ex-smokers and just 10% of never-smokers experienced dysphagia as a late-occurring side effect. Current smoking also was linked to higher rates of mucosal edema, atrophy, fibrosis, dry mouth, and hoarseness or loss of voice compared with outcomes in ex- and never-smokers.
Dorthe Wiinholdt
These findings highlight the importance of smoking cessation before and even during treatment, said Dorthe Wiinholdt, M.P.H., a radiotherapy technician nurse from Copenhagen University Hospital.
"As nurses, we see patients every day with side effects during treatment," she said May 9 at the European Society for Therapeutic Radiation Oncology Anniversary Conference. "We talk to them about quitting smoking before treatment, because we know that smoking has an influence on efficacy and quality of life, and [in this study] we wanted to know if there was anything that patients could do for themselves to decrease the severity of these side effects."
To examine the influence of smoking on late side effects commonly associated with radiotherapy, Ms. Wiinholdt and her colleagues used prospectively collected data from the Danish Head and Neck Cancer Study Group (DAHANCA)’s database.
Between January 2000 and March 2009, they identified 578 men and 217 women with head and neck cancer who had been treated with radiotherapy at Copenhagen University Hospital. The mean age of patients was 60 years.
Treatment consisted of 66-68 Gy for carcinoma of the larynx, pharynx, and oral cavity, with less than 10% receiving concomitant chemotherapy. In the majority (84%) of cases, treatment was intended to cure the cancer.
Before starting treatment, 60 (7.5%) patients were identified as never-smokers, with 290 (36.5%) defined as ex-smokers and the remaining 445 (56%) as current smokers. "Sixty percent of patients quit smoking during treatment, but one-third resumed smoking after treatment," Ms. Wiinholdt reported.
Of the six side effects associated with head and neck radiotherapy included in the analysis, dysphagia and mucosal edema were the most significant in relation to smoking.
Dysphagia occurred in 34% of current smokers, 21% of ex-smokers, and 15% of never-smokers 6 months after stopping radiotherapy, and in 31%, 20%, and 10%, respectively, 1 year after treatment cessation. Corresponding figures for mucosal edema were 25%, 19%, and 10% at 6 months, and 22%, 14%, and 5% at 1 year.
With never-smokers as the reference group, the odds ratios (OR) were 4.3 (P = .02) for the association between smoking and dysphagia and 4.2 (P = .01) for smoking and mucosal edema after 12 months.
"We also saw a significant correlation between daily tobacco use and the number of moderate to severe side effects," Ms. Wiinholdt noted, with respective odds ratios at 6 and 12 months of 2.71 (P = .006) and 2.54 (P = .009).
Importantly, quitting smoking during treatment was found to significantly reduce the severity of voice changes (OR, 1.78; P =.04) and mucosal edema (OR, 1.89; P = .03) after 6 months.
"These findings back up our advice that patients should stop smoking," Ms. Wiinholdt suggested. They not only emphasize the importance of quitting smoking before starting treatment, she added, but also highlight the continued need to support patients with smoking cessation initiatives during treatment.
Ms. Wiinholdt had no financial conflicts of interest.