FRIDAY, Jan. 6, 2017 (HealthDay News) -- Lung cancer chemotherapy that's been delayed due to slow recovery from surgery can still provide real benefit to patients, a new study suggests.

The study involved thousands of patients with non-small-cell lung cancers (NSCLC), which comprise about 90 percent of all lung tumors. Lung cancer remains the leading cancer killer in the United States.

As the study authors explained, chemotherapy is a standard part of treatment for people who've already had surgery to treat tumors that are larger than 4 centimeters (about 1.5 inches) or that have spread to the lymph nodes.

Typically, this post-surgical chemotherapy begins within six weeks of the surgery. However, not all patients are able to tolerate chemotherapy so quickly after their operation, including those who develop surgical complications.

So, a team led by Dr. Daniel Boffa, from the Yale School of Medicine, wondered if post-op chemo was still worth it, even if delayed beyond those six weeks.

To find out, Boffa's team tracked a U.S. national cancer database involving more than 12,000 patients. The researchers compared the timing of post-surgical chemotherapy against the odds the patient would die over the next five years.

All of the patients included in the study had stage I, II or III non-small-cell lung cancers.

The researchers found that delaying chemotherapy -- even when administered up to four months after surgery -- didn't increase a patients' risk of death.

And compared to patients who only had surgery with no follow-up chemo, those who had delayed chemotherapy still had a lower risk of death during the study period.

Based on the findings, "clinicians should still consider chemotherapy in appropriately selected patients who are healthy enough to tolerate it, up to four months after (non-small-cell lung cancers) surgical resection," Boffa said in a Yale news release.

However, the new study couldn't confirm a cause-and-effect link between the chemotherapy and extended survival, so "further study is warranted to confirm these findings," Boffa said.

Two lung specialists said the new findings have value.