Do Women Need Lung Cancer Screening Less Often Than Men?

Liam Davenport

May 08, 2017

GENEVA — Women should be screened for lung cancer less often than men because of the more favorable characteristics of their tumors, thereby reducing unnecessary radiation exposure and worry, say Korean investigators.

Their analysis of 17 years of results from low-dose computed tomography (CT) lung cancer screening conducted in Korea suggests that men should continue to be screened annually, while women could be screened every 3 years.

The new data were reported in a poster presentations here at European Lung Cancer Conference (ELCC) 2017.

However, experts discussing the new findings at the meeting questioned the researchers' conclusions, and in a keynote lecture, Harry J. de Koning, MD, PhD, professor of public health and screening evaluation at Erasmus Medical Center, University Medical Center Rotterdam, the Netherlands, said that he did not agree that the screening intervals should differ between men and women.

The US Preventive Services Task Force recommends annual CT screening for lung cancer in adults aged 55 to 80 years who have a smoking history of 30 pack-years and currently smoke or have quit smoking within the past 15 years.

Lead author of the new study, Mi-Young Kim, MD, a radiologist at the University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea, said, "Our study suggests that the annual follow-up interval for CT is too frequent for women, and scans every 2 to 3 years might be suitable."

"By reducing the number of unnecessary CT scans, we can decrease radiation exposure and increase cost effectiveness," Dr Kim added in a statement.

Nevertheless, Dr Kim highlighted that the number of female patients "was low, and further studies are needed to confirm the sex differences we found."

Commenting on the findings in a conference press release, Pilar Garrido, MD, PhD, head of the Thoracic Tumour Section of the Medical Oncology Department at Ramón y Cajal University Hospital, Madrid, Spain, said, "Several studies have highlighted that lung cancer has different features in women compared with men, thereby defining a different entity in female patients."

Noting the expected increases in cancer incidence and, therefore, burden on healthcare resources, she added: "Personalized screening strategies, such as a gender approach, could be a way to optimize results and allocate resources appropriately."

However, Dr Garrido emphasized, "The benefits, harms and feasibility of implementing gender-based lung cancer screening policies should be assessed and compared with those of current recommendations."

Differences Between Sexes

Dr Kim and colleagues point out that the clinical and radiologic presentation differs between men and women, particularly in Asia, and women are diagnosed with less advanced disease than men.

To examine sex-related differences in newly developed lung cancer and determine the optimal CT screening interval, the team retrospectively examined the records of 46,766 individuals who underwent CT screening between 2000 and 2016 at the Asan Medical Center of Korea.

Of the 282 newly diagnosed lung cancer cases during the study period, 186 detected on initial screening CT were excluded. The remaining 96 patients, who were diagnosed on follow-up CT screening, of whom 85 were male, were included for analysis.

Age did not significantly differ between men and women. However, men were significantly more likely than women to be smokers, at 87% vs 18%, respectively (P < .001).

The average time interval from previous CT scan to diagnosis with lung cancer on the subsequent CT scan was shorter in men than in women, at 3.1 years vs 5.6 years (P = .015). However, men were less likely to be diagnosed in stage I than women (49% vs 82%) and more likely to be diagnosed in stage IV (26% vs 18%).

Solid nodules were the most common tumor type in men (seen in 72%), while glass-opacity nodules were the most common finding in women (seen in 45%), followed by solid tumors (36% of cases). The mean tumor size was larger in men than women, at 29.5 mm vs 15.5 mm (P = .04).

The most common tumor pathologic type in men was adenocarcinoma, in 42% of cases, followed by squamous cell carcinoma in 35%, small cell lung cancer in 18%, and others in 5% of cases. All female patients had adenocarcinoma.

No Difference in Screening Interval 

During the meeting, Dr de Koning mentioned the Korean findings during a keynote lecture on the implementation of lung cancer screening.

He discussed a recent paper by ten Haaf and colleagues, which showed that, in the National Lung Screening Trial, adenocarcinomas were detected around 4.5 years earlier in men who underwent CT screening than in those who did not, while squamous cell carcinomas were detected around 5 years earlier and small cell lung cancers 3 years earlier.

In women, small cell lung cancers and squamous cell carcinomas were again detected with CT scanning around 3 and 5 years earlier, respectively. However, adenocarcinomas were detected 6 years earlier in women who were screened compared with those who were not.

Dr de Koning said that although the NSLT data suggest "you can detect women a little bit earlier than men," the difference "is not huge."

"So, I would certainly not say you should do [screening] differently by male or female gender," he concluded.

European Lung Cancer Conference (ELCC) 2017. Abstract 18PD. Presented May 6, 2017.

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