PHOENIX – Patients with a history of head and neck, lung, bladder, and hematologic malignancies had increased rates of subsequent non–small cell lung cancer (NSCLC), a large analysis of national data found.
“It is unclear to what extent the higher rate of primary NSCLC in these patients may be attributed to smoking, previous cancer history, or other lung cancer risk factors,” researchers led by Dr. Geena Wu wrote in an abstract presented during a poster session at the annual meeting of the Society of Thoracic Surgeons. “Further research using individual smoking data may better delineate who is at increased risk of NSCLC based on prior cancer site and smoking history.”
In a study that Dr. Wu led during a research fellowship at the City of Hope National Medical Center, Duarte, Calif., she and her associates used the Surveillance, Epidemiology, and End Results (SEER) 1992-2007 dataset to identify 32,058 patients with a prior malignancy who subsequently developed primary lung cancer at 6 months or more after their initial cancer. They calculated standardized incidence ratios (SIRs) for NSCLC as a rate of observed to expected NSCLC cases adjusted by person-years at risk, age, gender, and time of diagnosis.
The researchers found that patients with a history of the following cancers had higher rates of second primary NSCLC than expected: head and neck (SIR, 4.00), colon and rectum (SIR, 1.16), pancreas (SIR, 1.44), lung (SIR, 4.88), bladder (SIR, 1.97), kidney (SIR, 1.21), breast (SIR, 1.09), and leukemia or lymphoma (SIR, 1.40).
At the same time, patients with a history of pancreatic or breast cancer who were treated with radiation had a higher incidence of second primary NSCLC (SIR of 2.54 and SIR of 1.14, respectively), while those who were not treated with radiation did not.
Although the SEER database does not contain information about patient smoking history, the researchers evaluated adult smoking rates by state by using a national map from the Centers for Disease Control and Prevention’s 2013 Behavioral Risk Factor Surveillance System. Smoking rates were low (defined as 13.7% or less) in California, Hawaii, and Utah, and were higher in all other states, especially in Southeastern states. Dr. Wu and her associates found that patients from high smoking areas who had previous cancers of the colon and rectum, pancreas, kidney, thyroid, and breast had higher rates of a primary NSCLC, while those from low smoking areas did not. Interestingly, patients from high smoking areas who previously had uterine cancer, prostate, or melanoma had did not have higher rates of a primary NSCLC.
“Just because someone has a previous history of cancer, they’re not necessarily at increased risk of a second lung cancer,” Dr. Wu, who is now a fourth-year general surgery resident at Maricopa County Hospital in Phoenix said in an interview at the meeting. “You have to look at what kind of cancer they had and what their smoking history is – whether or not they continue to smoke, because smoking is such an important risk factor.”
Another limitation of the SEER database is that it lacks details about the type of chemotherapy patients receive, “so whether or not chemotherapy plays an impact in the elevated risk of lung cancer we can’t say.”
Dr. Wu reported having no financial disclosures.