Quitting Smoking Even After Lung Cancer Diagnosis Worth Doing

Patients who quit smoking at or around the time of a lung cancer diagnosis live longer than those who continue to smoke, concludes a new meta-analysis.

“Smokers who quit smoking at or around lung cancer diagnosis have a 29% improvement in their overall survival compared with those who continue smoking,” Saverio Caini, MD, PhD, Institute for Cancer Research, Prevention and Clinical Network, Florence, Italy, and colleagues observe.

“Treating physicians should educate lung cancer patients about the benefits of quitting smoking even after diagnosis and provide them with the necessary smoking cessation support,” they stress.

The study was published in the May issue of the Journal of Thoracic Oncology.

“It is time to stop ignoring the obvious and to fully integrate smoking cessation into quality cancer care,” experts comment in an accompanying editorial.

Meta-Analysis of 21 Studies

A total of 21 studies published between 1980 and 2019 were included in the systematic review and meta-analysis, with around 15,000 patients overall, including 5315 patients with a diagnosis of nonsmall-cell lung cancer (NSCLC), 5133 patients with small-cell lung cancer (SCLC), and 4490 patients with lung cancer of both or unspecified subtypes.

“In most studies, quitters were those who stopped smoking at diagnosis or at some point thereafter,” the investigators explain.

Quitting smoking at or around the time of diagnosis was significantly associated with a 23% improvement in overall survival for patients with NSCLC, regardless of the histologic subtype (P = .812) and a 25% improvement in overall survival for patients with SCLC compared with those who continued to smoke, the authors report.

Furthermore, quitting smoking at or around the time of diagnosis seemed to be beneficial for patient prognosis even when evaluating endpoints other than overall survival, the authors continue.

For example, among the patients with NSCLC, quitters experienced a 30% longer progression-free survival in at least one study, while another study found that quitters had a 46% longer disease-free interval.

Several other studies support the observation that patients with SCLC who quit smoking enjoy significantly longer disease-free survival than nonquitters.

Another study found that locoregional control of lung cancer was again 46% longer among patients who quit smoking than among those who continued to smoke, although these positive benefits were not consistently seen in all studies.

As the authors observe, smoking promotes tumor growth, progression, and dissemination. It also decreases the efficacy of — and tolerance to — radiation and systemic therapy and increases the risk of postoperative complications and secondary primary cancers.

On the other hand, patients who quit smoking at or around the time of cancer diagnosis may differ from nonquitters in terms of demographics or tumor characteristics that could also affect survival, the authors comment.

Quitters may also be more likely to receive resection with curative intent and patients with earlier-stage lung cancer might be more motivated to quit smoking in order to enhance their likelihood of recovery. “Lung cancer remains a disease with a generally poor prognosis, despite the advances that have occurred over the past decade, including the introduction of immune checkpoint inhibitors (alone or in combination) effective for both NSCLC and SCLC,” Caini and colleagues observe.

They also observe that lung cancer screening could serve as a “teachable moment” to help patients quit smoking by integrating a cessation program into screening activities, which would benefit not only those testing negative on screening but also those eventually diagnosed with lung cancer.

Declining Incidence/Mortality

Commenting on the findings in an editorial, William Evans, MD, McMaster University, Hamilton, Ontario, Canada, and colleagues comment that “smoking is the common theme across the continuum of cancer risk diagnosis and treatment.”

“Continued smoking after a cancer diagnosis increases the risk of overall and cancer-related mortality by a median of 50% to 60% across disease sites and treatments,” they warn.

In contrast, results from the current study suggest that the survival gains achieved by quitting smoking at or after a cancer diagnosis could rival those achieved with modern therapeutic approaches.

“It is important to note that the benefits of quitting smoking were obtained in combination with standard lung cancer treatment and that smoking cessation support did not compromise the therapeutic benefits achieved with evidence-based NSCLC treatment,” Evans and colleagues point out.

Despite this, large surveys of oncologists have revealed that most of them do not regularly help patients with smoking cessation, they observe.

Efforts both in Canada and the United States are underway to increase access to smoking cessation in cancer care, including the Just ASK initiative being disseminated at US cancer centers this year.

In the meantime, the editorialists emphasize that patients clearly do worse if they keep smoking.

“Patients need to clearly understand that smoking negatively affects their cancer treatment and that smoking cessation could improve their outcomes. This discussion needs to occur as soon as patients begin their diagnostic workup or treatment,” the editorialists comment.

“When smoking cessation could improve survival by 20% to 35%, as suggested by Caini et al [in this meta-analysis], should not every patient have the opportunity to achieve the best possible outcomes?” they continue. “Shouldn’t every care provider want that for their patients?”

The study was supported by the Italian Ministry of Health. The authors and editorialists have reported no relevant financial relationships.

J Thorac Oncol. 2022;17:596-598, 623-636. Full text, Editorial

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