(RxWiki News) Smoking is a major cause of lung cancer and has been linked many other cancers. Although survival rates may be improving for smoking-related cancers, survivors may face greater odds of getting a second cancer.
The National Cancer Institute (NCI) reports that cancer survival rates have been on the upswing because of advances in the ways that cancer is diagnosed and treated. For those with lung cancer, there has been a small but significant rise in survival over the past three decades.
Those who smoke or have smoked, however, may face a tougher battle when it comes to cancer. A new study found that cancer survivors who smoked prior to their first diagnosis of cancer may be more likely to develop a second smoking-related cancer.
Meredith S. Shiels, PhD, a research fellow with the NCI's Division of Cancer Epidemiology and Genetics in Bethesda, MD, led the research.
Dr. Shiels and colleagues reviewed data from five large cancer studies. The studies represented 2,552 patients with stage 1 lung cancer, 6,386 with bladder cancer, 3,179 with kidney cancer, and 2,967 with head and neck cancer.
The study authors found that cancer survivors who smoked more than 20 cigarettes per day were up to five times more likely to develop a second, unrelated cancer than those who had never smoked.
Risk levels, however, were lower among those who had quit smoking after their first diagnosis compared to those who continued to smoke. Cancer survivors who had smoked more than 20 cigarettes a day but quit had a 2.35 times greater risk of getting a second cancer. The same cancer survivors who continued to smoke that much had a 5.41 times greater risk.
Current smokers with a habit of fewer than 20 cigarettes per day still faced a 3.72 times greater risk for getting a second cancer.
Dr. Shiels and team noted that risks decreased in relation to the number of years since a person quit smoking.
“Our data indicate that cigarette smoking before first cancer diagnosis increases second cancer risk among cancer survivors, and elevated cancer risk in these survivors is likely due to increased smoking prevalence,” the authors wrote.
In a press release, Dr. Shiels added that the study demonstrates why doctors should emphasize the importance of quitting smoking to all their patients — including cancer survivors.
The study was published Nov. 10 in the Journal of Clinical Oncology.
The Intramural Research Program of the National Cancer Institute funded the study. The authors listed conflicts of interest on the journal website.