MONDAY, Jan. 23, 2006 (HealthDay News) -- A tiny fraction of patients with incurable lung cancer survived five or more years past diagnosis after receiving low-dose radiation intended merely for pain relief, a team of Australian researchers report.
"About one in every hundred patients with non-small cell lung cancer appear to have disease that is remarkably sensitive to treatment with radiotherapy," noted Dr. Michael Mac Manus, an associate professor in the department of Radiation Oncology at the Peter MacCallum Cancer Center in East Melbourne. "Some of these patients seem actually to have been cured by a therapy usually considered to have no curative potential whatsoever."
"If we could understand why some patients can apparently be cured by non-aggressive therapies, we might be able to develop treatments that could benefit all lung cancer patients," Mac Manus said.
According to the American Cancer Society, there are more than 172,000 new cases of lung cancer each year in the United States, accounting for approximately 13 percent of all new malignancies. The leading cause of cancer death, lung cancer claimed the lives of an estimated 163,000 Americans in 2005 -- more than all deaths from colon, breast and prostate cancer combined.
Most lung cancers (87 percent) are diagnosed as non-small cell lung cancers (NSCLC). The remaining 13 percent of patients are diagnosed with more aggressive small cell lung cancer (SCLC), which almost exclusively strikes smokers.
Often caught at a late stage of progression, the disease kills almost 60 percent of patients within a year of diagnosis. Almost 75 percent will succumb within two years, and just 15 percent survive a full five years post-diagnosis.
In their study, Mac Manus and his team focused on nearly 2,300 Australian men and women diagnosed with NSCLC between 1984 and 1990. All the patients had been deemed incurable, and therefore were ineligible for high-dose radiation therapy.
Instead, all the men and women received low-dose, palliative radiation therapy for a maximum of 68 days, after which point they were closely monitored through regular physical exams and chest radiographs.
Reporting in the March issue of Cancer, the authors say the average survival time post-diagnosis was just under five months.
However, a little more than 1 percent of the patients -- about 24 men and women -- survived to the five-year mark. About one-third of these five-year survivors went on to survive another five years.
Eighteen of the 24 patients were deemed "cured" after their cancer stopped progressing by the five-year juncture. There was a 43 percent chance they would survive another five years and a 78 percent probability that their disease status would continue to be "progression-free."
There were some key differences between these survivors and the rest of the study pool. First, they had retained more robust physical function at the time of their lung cancer diagnosis than those who didn't ultimately make it. Their cancers were also less likely to have spread far beyond the initial tumor.
But the researchers could not identify any common thread accounting for the patients' survival. Pre-treatment optimism, initial misdiagnoses, use of unconventional medicine, and/or "faith healing" did not account for their unlikely longevity, the researchers said.
The Australian team said their finding should give newly diagnosed lung cancer patients some small reason for hope.
"Patients treated with palliative radiotherapy for lung cancer remain very unlikely to become long-term survivors, but there is still a very small chance for cure," said Mac Manus. "Knowledge of this possibility may be enough to keep hope alive and improve quality of life for some patients. It may also influence the choice of therapy when a patient is offered a number of different treatment options."
But he added that no one yet knows why these patients beat the odds.
"This is a significant but entirely unexplained phenomenon, and our study has given no hint of an explanation," he admitted. "We believe that an investigation of the molecular biology of the tumors of unexpected long-term survivors and of the state of immunity of the surviving patients should be carried out."
Dr. Neil Schachter, medical director of the respiratory care department at Mount Sinai Medical Center in New York, said the finding is interesting, but not revolutionary.
"Any finding in this field that is not dismal is to be considered encouraged, and I would of course want to be positive about any potentially beneficial treatment for an otherwise incurable lung cancer," Schachter said. "But this doesn't sound to me like a breakthrough."
Physicians have long known that regardless of treatment type, a very small group of patients do go on to survive lung cancer despite a gloomy initial prognosis. And he cautioned that the current study might simply have stumbled upon a similar pool of patients by happenstance -- patients who would have survived with or without the minimal radiation they received.
"These researchers are carefully singling out the fact that the 1 percent of patients who lived past five years went into remission or were cured. This means they survived well. So there may be some element of good hope in all of this," Schachter said.
More information
For more on lung cancer, check out the American Cancer Society.
