LOUISVILLE, Kentucky--Photodynamic therapy (PDT) offers a simple and
effective alternative to conventional techniques for palliative
debridement of endobronchial obstructions in lung cancer patients,
data from two clinical trials suggest.
Compared to YAG laser treatment, PDT with porfimer sodium (Photofrin)
demonstrated better efficacy for relief of obstructions and
improvement in dyspnea and cough. Aside from photosensitivity
reactions, systemic adverse effects of the two treatments were similar.
"A large proportion of patients with advanced lung cancer have
symptoms of dyspnea, coughing, and hemoptysis, which has a major
effect on quality of life," said
Thomas J. Wieman, MD, an oncologist at the University of Louisville,
Kentucky. "Many times, if the symptoms can be alleviated, the
patients can lead fairly independent lives, at least for the 6 or 9
or 12 months they have remaining."
In his poster presentation at the ASCO meeting, Dr. Wieman reviewed
data from two randomized comparisons of Photofrin and the Nd:YAG
laser in patients who had endobronchial obstruction related to
advanced lung cancer. For statistical analysis, he and his colleagues
combined data from the two trials, which involved a total of 198
Photofrin is a photosensitizer that produces a local, selective
cytotoxic reaction when activated by red nonthermal laser light, Dr.
Wieman said. Previous studies have demonstrated efficacy of the
treatment in obstructive esophageal cancer (Gastrointest Endosc
Photodynamic therapy with Photofrin comprises a two-step process: (1)
The photosensitizer is injected intravenously and selectively
retained by tumor tissue. (2) Two days later, a 630 nm wavelength
nonthermal red light is directed at the tumor, activating the
retained photosensitizing agent.
Generation of free radicals leads to a selective, direct cytotoxic
effect on the tumor. Necrotic tissue is debrided 2 days after light
exposure to prevent obstruction and associated severe dyspnea.
In the trials, a second light exposure was optional at the treating
Treatment with the Nd:YAG laser consisted of unlimited energy
applications until all accessible tumor was ablated.
A complete response was defined as total ablation of all
endoscopically viable tumor; a partial response was an increase of at
least 50% in the smallest luminal diameter. In this analysis,
complete and partial responses were combined into an overall response rate.
Results of the two trials showed response rates of approximately 60%
for both therapies at the end of 1 week. At 1 month, significantly
more patients treated with photodynamic therapy maintained their
responses, 55% vs 29% of patients treated with the laser.
Also at 1 month, symptom palliation favored PDT for all symptoms
assessed (dyspnea, cough, hemoptysis, sputum, and percent of patients
with a clinically important benefit from therapy). Significantly more
patients treated with Photofrin had improvement in dyspnea and cough,
30% and 27%, respectively, vs 17% and 13%, respectively, for laser treatment.
Systemic toxicity was similar for the two treatments with the
exception of photosensitivity reaction, which occurred in 20% of
Photofrin patients and none of the laser-treated patients. The
incidence of fever and pain did not differ between the two groups.
Pulmonary adverse effects were significantly more common with PDT,
especially dyspnea (32% vs 17%) and bronchitis (11% vs 3%).
Neither treatment was associated with improved survival. Median
survival was 166 days in patients treated with PDT and 157 days in
the laser-treated group.
"PDT is simpler to perform and leads to a better functional
result, at least over the short term," Dr. Wieman said.
"Its hard to measure long-term effects because the
patients have so many systemic problems and a brief life expectancy."