Lung cancer detected earlier in breast cancer patients

Lung cancer screening criteria may not be wide enough to capture significant numbers of people with no smoking history. This comes from researchers who conducted a study published in BJS Open which found that women with a history of breast cancer who later developed lung cancer were found to have earlier detection than women with no breast cancer history. Women with a history of breast cancer tend to undergo follow-up screening for breast cancer recurrence, and that if lung cancer is present it is caught earlier—as an incidental finding, said the study’s senior author Dr. Daniela Molena. Molena, an associate professor of surgery at the Memorial Sloan Kettering Cancer Center MSKCC, noted that the United States Preventive Services Task Force (USPSTF) guidelines for lung-cancer screening do not include previous malignancy as a risk factor. Screening guidelines focus on smoking history and age, but she questioned whether there should be additional criteria such as history of previous cancers, such as breast cancer, should be added. “There are a lot of patients with lung cancer that don’t smoke, or are exposed indirectly to other substances that we know that can cause lung cancer,” she told CanadianHealthcareNetwork in an interview. And yet “Women and racial and ethnic minorities have been repeatedly shown to have a higher risk of developing lung cancer with a shorter or lighter smoking history, and these individuals are often not considered eligible for screening… As a result, most clinical trials do not adequately represent female patients, and often conclusions taken from studies that include mostly men are applied to women,” according to the study. More work needs to be done to elucidate which other groups would benefit from earlier lung cancer screening, said Dr. Molena. The study was conducted to compare women with and without a history of breast cancer who underwent resection for lung cancer—to assess whether there were differences in stage at diagnosis, survival and eligibility for lung-cancer screening between the two groups. Using the MSKCC database, researchers extracted data for all women who presented for lung cancer resection between January 2000 and December 2017. Only patients who underwent surgical resection for a first-time lung cancer were included. Characteristics and outcomes were compared between patients with a history of breast cancer before lung cancer (BC-Lung), and patients with primary lung cancer with no history of breast cancer (P-Lung). The before-lung cancer group included women with a diagnosis of breast cancer, ductal carcinoma in situ and lobular carcinoma in situ at any time before lung-cancer diagnosis. Data for a total, of 2,192 patients were included. Of these, 331 patients (15.1%) were in the BC-Lung group and 1,861 (84.9%) were in the P-Lung group. Demographic and clinicopathological characteristics and treatment and survival data were analyzed. The most common method of lung cancer diagnosis among patients in the BC-Lung group was breast cancer surveillance or work-up imaging (154 of 331 patients, 46.5%)—nearly half. The median interval between breast cancer diagnosis and lung cancer diagnosis was 110 months. Most patients had early-stage breast cancer and 61.0% had received breast radiation therapy. When it came to comparing the BC-Lung and the P-Lung groups, a number of features stood out. For one, the BC-Lung group were older at the time of lung cancer diagnosis (a median of 70 versus 67 years). Importantly, the tumour size detected by CT scans tended to be significantly larger in the P-Lung group than in the patients with past breast cancer. In addition, patients in the P-Lung group had more advanced clinical T-stage tumours and were more likely to have node-positive disease. “There were no statistically significant differences in histological subtype between the groups; however, patients in the BC-Lung group had earlier-stage disease,” the study said. Oddly, there was no significant difference in survival between the groups. Overall 5-year survival was 73% for the P-Lung group and 73% for the BC-Lung group. “That was a bit of a surprise for us. We thought if you’re diagnosed with cancer at an early stage, you should see a benefit in survival… I don’t know if that’s a fact that we didn’t have a lot of patients. Maybe if we had a larger group of patients we’d see a difference, or maybe there are other factors associated with worse prognosis even with earlier stage in the setting of previous cancer,” said Dr. Molena. When it came to risk factors and qualifying for USPST lung cancer screening, many of the women with a history of breast cancer would not have qualified for screening – they tended to be younger and fewer packyears. Overall, 58.4% of patients (1,281) had a history of smoking. Using the 2020 USPSTF guidelines, 44.9% (985) of the overall study cohort met the criteria for screening. “Doctors should really be thoughtful in evaluating the risk factors of women, especially if a patient has a history of cancer in the past,” she said. Spokespeople from Lung Cancer Canada and other experts were unavailable for comment. The Canadian Task Force on Preventive Health Care recommends screening of high-risk individuals adults aged 55 to 74 years who currently smoke or quit less than 15 years ago, with a smoking history of at least 30 pack-years. The guidelines add “We recommend not screening all other adults, regardless of age, smoking history or other risk factors, for lung cancer with low-dose CT.”

Lung cancer detected earlier in breast cancer patients

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