Radiation May Help Those With Inoperable Lung Tumors
TUESDAY, March 16 -- A carefully targeted and powerful regimen of radiation therapy kept early-stage lung tumors stable in patients who had inoperable cancers.
Almost 56 percent of patients who underwent the therapy, called stereotactic body radiation therapy (SBRT), were still alive three years after their treatment, according to preliminary findings from a study published in the March 17 issue of the Journal of the American Medical Association, a themed issue on cancer.
By contrast, only about 25 percent to 30 percent of patients who receive conventional fractionated radiotherapy survive that long.
"Stereotactic body radiation therapy controlled peripheral small tumors in a large majority of patients and had an impressive overall survival rate at three years," said study lead author Dr. Robert Timmerman, professor of radiation oncology at the University of Texas Southwestern Medical Center at Dallas, speaking at a Tuesday teleconference.
Unfortunately, the risk of the cancer spreading to other parts of the body was still high, the researchers noted.
The U.S. National Institutes of Health-funded Radiation Therapy Oncology Group is planning further trials to refine the procedure.
"The study was done by the leading radiation therapy research group in the world but it was very small," commented Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge. "It's provocative but it's not for all patients with lung cancer. This is for people who can't undergo surgery, so I think surgery is still the best way to treat early lung cancer," Brooks said.
"The radiation was effective at controlling the cancer in the spot but the cancer still has a high risk of spreading to other parts of the body," he added.
Patients who cannot undergo surgery for early-stage lung cancer tend to be frail, with many other medical conditions. They are therefore unable to withstand invasive procedures that would track cancer recurrence, and even the initial biopsy can pose a risk.
Standard treatment right now for these patients is conventional radiation treatment given every weekday for six weeks, or simply observation with supportive care.
In addition to a high mortality rate, only 30 to 40 percent of these patients see their tumors controlled, meaning they don't grow. Some 8,000 to 10,000 patients in this group are diagnosed each year in the United States, Timmerman said.
"Stereotactic body radiation therapy uses numerous small beams that converge on the target. Each beam is fairly weak [although the overall effect is strong] so there's not as much entry damage and each beam, being very small, has to be guided very carefully with image guidance," Timmerman explained.
This study involved 55 patients with inoperable early-stage non-small cell lung cancer, the most common type of lung cancer. Individual tumors were small with most measuring 3 centimeters or less.
Treatment involved 20- to 60-minute sessions one to five times a day or every other day. The entire course of therapy lasted only one-and-a-half to two weeks.
Three years after treatment, almost 98 percent of primary tumors were controlled; local control (the primary tumor and the lobe) was close to 91 percent; and the local-plus-regional control rate was just over 87 percent. This was about double the rate seen with conventional radiotherapy.
Just over 48 percent of participants made it to the three-year mark without a recurrence of their disease.
Disappointingly, 11 patients (22.1 percent) did develop distant metastases, eight of them within two years. The authors speculated that these patients already had metastases that were not detected at the time of diagnosis. But the rate of these recurrences was higher in patients with a certain type of larger tumors, suggesting there may be ways to address this.
Many individuals also had treatment side effects including rib fractures, chest-wall burns, painful swallowing and fluid build-up around the heart.
And the researchers note that many patients continued to smoke throughout and after their treatment.
"There's definite room for improvement moving forward with therapies," Timmerman said.
Timmerman reported receiving monies from two companies who manufacture equipment used in SBRT. The study itself, however, was not funded by private interests.
Learn more about lung cancer at the U.S. National Cancer Institute.
Posted: March 2010