Decline in Lung Cancer Mortality Affects Decreases in Overall Cancer Deaths

Reductions in lung cancer mortality are driving the steady decline in overall cancer-associated deaths, according to study findings published in CA: A Cancer Journal for Clinicians.

Researchers from the American Cancer Society compiled incidence and mortality data as collected by the Surveillance, Epidemiology, and End Results Program (SEER); the National Program of Cancer Registries; the North American Association of Central Cancer Registries; and the National Center for Health Statistics. Incidence data were included through 2016 and mortality data through 2017.

The researchers estimated the total number of cancer deaths that have been averted as a result of the continuous decline since the early 1990s. The cancer death rate rose steadily until 1991 and then began to fall through 2017, which produced an overall decline of 29%, or an estimated 2.9 million fewer cancer deaths.

In projecting estimated new cancer cases in the United States in 2020, the researchers found the highest number of expected cancer deaths are due to lung, prostate, and colorectal cancer in men, and lung, breast, and colorectal cancer in women. Overall, approximately one-quarter of all expected cancer deaths are from lung cancer.

Since 1991, the incidence of lung cancer has declined twice as fast in men as it has in women (51% vs 26%, respectively), which the researchers noted “reflect[s] historical differences in tobacco uptake and cessation, as well as upturns in female smoking prevalence in some birth cohorts.” However, declines in smoking and improvements in detection and treatment have resulted in a continuous decline in the cancer death rate. Declines were notable in the lung cancer death rate specifically — from 3% annually (2008 through 2013) to 5% (2013 through 2017) in men and from 2% to nearly 4% in women during the same periods.

The American Cancer Society and the US Preventive Services Task Force recommend low-dose computed tomography (LDCT) in certain current/former heavy smokers, but many individuals are inappropriately screened, making it difficult to extend the benefit of testing to the general population.

The researchers noted that according to the National Lung Screening Trial, lung cancer mortality risk was reduced by roughly 20% in current/former smokers with ≥30 pack-year history who were screened with LDCT compared with chest radiography. They also noted that in an Italian study with more screening rounds, a more moderate risk pool (individuals with ≥20 pack-year history), and a longer follow-up, lung cancer mortality was reduced by 39% compared with no intervention.

“Broad implementation of recommended lung cancer screening will require new systems to facilitate unique aspects of the process, including the identification of eligible patients and the education of physicians regarding details of the shared decision-making conversation required by the Centers for Medicaid and Medicare Services,” the investigators wrote.

Pulmonology Advisor reached out to Rebecca Siegel, MPH, one of the investigators, to learn more about the advances that have improved lung cancer outcomes, as well as what measures should be taken for the future.

Editor’s Note: This interview has been lightly edited for length and clarity.

Pulmonology Advisor: Do we know which specific treatments can be attributed to some of the decline in lung cancer deaths?

Rebecca Siegel, MPH: Advances in lung cancer treatment across the board, from improved staging with integrated positron emission tomography-computed tomography scanning to advances in surgery such as video-assisted thoracoscopic surgery have not only improved outcomes, but extended the option of surgery to more patients. Stereotactic ablative radiotherapy and more targeted drug therapies have also contributed to the decline. It is due not one single treatment because there has been a similar improvement in survival since 2000 of approximately 10% in absolute terms for 1-year relative survival for every stage of diagnosis.

Pulmonology Advisor: Similarly, can you elaborate on the positive effect LDCT screening has had on lung cancer mortality? 

Rebecca Siegel, MPH: Screening offers hope for more early detection, but dissemination has been slow, especially among patients who are appropriate candidates, such as high-risk current/former smokers. Screening prevalence is approximately 14% according to the most recent data, which is for 2017, so it probably had little effect on the trends we reported in our study.

Pulmonology Advisor: The fact that the sharp decline in overall cancer deaths is being driven by lung cancer specifically is very telling. Do you believe this report will increase public awareness of lung cancer?

Rebecca Siegel, MPH: Absolutely. Lung cancer is by far the leading cause of cancer death, causing more deaths each year than breast, prostate, and colorectal cancers combined. The drop in mortality from 2016 to 2017 falls from 2.2% to 1.4% when lung cancer is excluded from the mix. Thus, despite the progress in reducing lung cancer incidence and extending survival for patients diagnosed with it, continued diligence to reduce smoking and understand the causes of this disease in nonsmokers is needed.

More attention to remove the stigma attached to lung cancer is critical, and it would be wonderful if this news pushes us in that direction. The demonstration of real improvement in lung cancer outcomes following years of stagnation could also be a catalyst for more positive attention.

Pulmonology Advisor: As more advances are made in lung cancer prevention and treatment such as new drugs, updated screening practices, and increased smoking cessation rates, do you foresee the decline in rates of lung cancer deaths among women catching up to the rates seen among men? 

Rebecca Siegel, MPH: Perhaps, because the pace of decline in women is starting to approach that in men, although lung cancer trends differ in men and women because of differences in smoking uptake and cessation.

Reference

Siegel RL, Miller KD, Jemal A. Cancer statistics, 2020 [published online January 8, 2020]. CA Cancer J Clin. doi:10.3322/caac.21590