The effect of
phototherapy on the growth of two human
tumors, i.e.
carcinoma of the rectum I and III, was studied. The
tumors were xenotransplated into athymic nu/nu mice. Meso-tetra-(para-sulfophenyl)-
porphin,
TPPS4, was used as
photosensitizer. Incorporation studies showed the optimal dose for
phototherapy to be 10 mg/kg
TPPS4 and the time interval 72 hours. Under these experimental conditions (
helium-neon
laser, 632, 8, 300 J/cm2) one of six
tumors was cured in the group with
carcinoma of the rectum I, and that both after IV and IT administration of the
photosensitizer. The other five experimental animals exhibited only partial responses to
phototherapy. In the group with
carcinoma of the rectum III, five out of six
tumors were cured by IT administration of
TPPS4 under the same experimental conditions. In one mouse there was only partial response to
phototherapy. After IV administration of
TPPS4, however, not a single
tumor was cured and the response to
phototherapy was only partial in all the six experimental animals.