Patients with non-small-cell lung cancer may live longer if they take beta-blockers while undergoing radiotherapy.
The finding came from new research conducted by a team of experts at the University of Texas MD Anderson Cancer Center (Houston, USA) and was published in Annals of Oncology.
A previous study in the same journal demonstrated that advanced radiotherapy was linked to improved survival rates among patients with lung cancer.
In the current study, the scientists analyzed the progress and results of 722 people who had undergone radiotherapy as their primary or 1st line of treatment for cancer (referred to as "definitive radiotherapy" - received at doses of at least 60 Gy, hoping to put an end to the disease).
Results showed that 155 subjects were receiving beta-blockers for high blood pressure, heart disease, or other issues other than cancer.
Those patients who took beta-blockers survived for an estimated 23.7 months as opposed to the 567 other subjects who were not taking them, who survived for approximately 18.6 months (a 22% increase after controlling for other variables such as stage of the cancer, age, the use of aspirin, chronic obstructive pulmonary disease, and whether or not chemotherapy was given simultaneously).
The use of beta-blockers was also linked with improvements in survival without the cancer coming back (disease-free survival) and survival without the disease spreading to other areas of the body (distant metastasis-free survival).
Beta-blockers did not impact the length of time a patient survived without the disease progressing to the area of the lungs where it had first come about (locoregional progression-free survival).
Assistant Professor Dr Daniel Gomez, at the Department of Radiation Oncology at the MD Anderson Cancer Center, explained:
"Despite recent improvements in radiotherapy and chemotherapy for non-small-cell-lung cancer, the prognosis of this disease is poor, with less than 15% of patients surviving for five years after diagnosis. A major cause of death is the process of metastasis, when cancer cells travel from the original tumor to other parts of the body. Therefore, we urgently need to find new ways of blocking the development of metastases in these patients.
Our results suggest that the use of beta-blockers during radiotherapy may help to prevent the formation of metastases, and could lead directly or indirectly to improved care for patients with non-small-cell lung cancer. As far as we are aware, our study is the first analysis to show a survival benefit associated with the use of beta-blockers during definitive radiotherapy in patients with NSCLC. However, prospective studies are needed to investigate these findings further and to discover whether improved survival is affected by when and for how long patients need to take beta-blockers. We are excited about using our study as a starting point for further investigations."
The procedures underlying the forming of metastases are complicated, however, they may include lengthened exposure to stress hormones and chronic stress conditions.
Norepinephrine, one of the stress hormones, has been known to stimulate the migration of tumor cells to other areas of the body. The process involves receptors on the surface of cells, which beta-blockers are made to obstruct.
Professor Zhongxing Liao, from the Department of Radiation Oncology at the MD Anderson Cancer Center, said:
"Our findings agree with results from previous studies suggesting that beta-blockers have a specific effect on the cascade of events that lead to metastases. The fact that their use did not affect locoregional progression-free survival suggests that the drugs affect this metastatic cascade rather than the primary tumor."
The subjects evaluated had received definitive radiotherapy at the MD Anderson Center from 1998 to 2010. The 155 people who were taking beta-blockers took a variety of different kinds of the treatment and required different doses.
There were not a sufficient number of patients, according to the team, to determine whether the selection of a beta-blocker is crucial. However, most of the patients in the report who did well were on a selective beta-blocker.
The authors pointed out that the research calls for further studies.
Prof Liao revealed: "Due to practical limitations, we were unable to assess whether any other medications that patients were taking while receiving radiotherapy may have influenced the results. This should be the subject of future analyses, ideally in clinical trials."
According to Dr. Gomez, the experts were exploring the option of a clinical trial to examine the effectiveness of novel therapies, including beta-blockers, for lung cancer. However, this would call for outside funding.
"Another future direction would be to examine further the molecular characteristics that lead to this apparent clinical improvement in survival. For instance, what cellular pathways are involved in patients that experience a benefit with beta-blockers, and can these mechanisms be altered in another way to achieve the same benefit?" Dr. Gomez concluded.