By Dan Vergano, Medical Tribune News Service
Some cases of stomach cancer went into complete remission
following treatment with antibiotics, report Texas researchers.
Many cancer experts now suspect that infections play a role in
triggering several types of cancer, said Dr. Gideon Steinbach of
the University of Texas M.D. Anderson Cancer Center in Houston, who
led the study. For example, human papilloma virus seems to spur
development of cervical cancer. Cancers of the lymph cells, immune
system stalwarts that travel throughout the body to rid it of
invaders, have been spotted at infection sites in the salivary
glands and lungs, said Steinbach, suggesting a connection.
Looking at gastric lymphoma, an uncommon type of immune cell
cancer found in the stomach, Steinbach's research team tested the
effects of antibiotic treatment on 34 patients with early or middle
stages of the disease. Lab tests revealed that 28 of study
participants also suffered from infection with H. pylori, a
bacterium that causes ulcers. The men received a regimen of several
antibiotics, such as tetracycline and amoxicillan, until their
infections cleared and were then observed for average of three
years afterward.
``We found this malignancy is dependent on H. pylori for growth
and in some patients it regresses with antibiotic treatment,'' said
Steinbach. Half of the patients who tested positive for H. pylori
achieved complete remission of the stomach tumors. None of the six
patients without the infection responded to the treatment.
Only one patient with cancer that had moved beyond his stomach
responded to the antibiotic treatment, said Steinbach. Patients may
need to receive antibiotics, typically two courses of different
antibiotics for years in order to clear up the most serious cases.
People with gastric lymphoma but no signs of H. pylori should
receive chemotherapy immediately, suggested Steinbach.
``Lymphoma cells look like normal cells. It's not clear how they
become tumors,'' he added. In most cases of cancer triggered by
infections, the tumor cells have mutated and no longer need the
infectious agent to continue their growth. Gastric lymphoma appears
to be unique in needing the infection to persist in some cases.
Steinbach theorizes that some growth factor brought to the
infection site by T cells, immune system cousins of the lymph
cells, stimulates the growth of the tumor cells. Inflammation at
the site of infections may be the trigger for other cancers of the
immune cells, an area under strong investigation by cancer
researchers. ``There may be some surprises ahead,'' said Steinbach.
Since tumors which had escaped beyond the stomach were less
likely to succumb to antibiotics, the researchers believe those
cancer cells have mutated past their dependence on H. pylori. For
those patients, radiation therapy may offer the only hope for
remission of the cancer, said Steinbach.
The Texas researchers have added more patients to their
antibiotic treatment group but have not analyzed their outcomes
yet. The study appeared in the Monday edition of Annals of Internal
Medicine, a publication of the American College of Physicians -
American Society of Internal Medicine in Philadelphia.
