Cancer is revealed in about 8 million people in the world annually, and over 5 million die
from this disease. In Russia about half-million malignant tumor are diagnosed every year.
The technique of oncologic patients’ treatment is known: radio- and chemotherapy, surgery.
But today photodynamic therapy becomes perspective instrument, helping to eliminate cancer.
Photodynamic therapy (PDT) is a nonsurgical method of tumour treatment. It is based
on selective accumulation of a certain light-absorbing preparations (photosensitizer) in the
tumor tissue, and following pathological tissue destruction after irradiation by light of
a certain wavelength. A photosensitiser is administered to the patient, usually by
injection. The photosensitiser alone is harmless and has no effect on either healthy or
abnormal tissue. However, when light (often from a laser) is directed onto tissue containing
the drug, the drug becomes activated and the tissue is rapidly destroyed, but only precisely
where the light has been directed. Necrosis of tumor tissue develops, pathological tissue
resorbs, and is gradually replaced by connecting tissue.
PDT procedure
Photodynamic therapy offers a number of advantages over traditional techniques for malignant
tumors (such as surgical operation, radiotherapy, and chemotherapy). First, PDT is highly
selective and targeted in action. Second, it is free of surgical risks, serious damages,
and systemic complications. Third, PDT sessions can be repeated as many times as needed.
Fourth, a single PDT procedure enables both the treatment and fluorescent diagnosis.
Finally, most patients exhibit tumor resolution after a single PDT cure, which can be
performed under outpatient conditions.
In our practice, we use the second – generation drug “Radachlorin”, produced by RADAPHARMA
Co (www.radapharma.ru) as a photosensitizer. Radachlorin &® is a derivative of the well-known
green pigment chlorophyll ?. Initial raw material for this drug is Spirulina platensis
microalga. This drug substance represents an aqueous solution of three chlorins,
including sodium chlorin e6 (90-95%) sodium chlorin p6 (5-7%), and a third chlorin t (1-5%).
Generally, chlorin constituents (called "chlorin active substance") of the drug are 98% of
its dry weight. Thus, Radachlorin® is a complex natural drug, accumulating and efficiently
destroying tumors upon photoirradiation (662 nm).
The drug is administered intravenously and within a period of 0.5-3 hours, selectively
concentrates in diseased cells or pathologically altered tissues while largely clearing
from normal tissues. Radachlorine remains inactive until exposed to laser light. When
applied, the laser energy, delivered to the relevant site, activates the drug. The
cumulative action destroys the tumor, however, does not inflict hurt to the normal tissues.
After the treatment a decomposition of tumor (necrosis) takes place for up to 2-3 weeks,
followed by regeneration of the wholeness of the normal tissue with an excellent cosmetic
effect
Chlorin photosensitizers produced radical changes in the PDT of malignant tumors. The
application of the most of other photosensitisers relies on a long-term treatment under
inpatient conditions, whereas the application of Radachlorin avoids this stage. Instead,
the patient receives a one-day or outpatient treatment. A tumor is irradiated 3 hours after
the photosensitizer injection.
Radachlorin treatment does not demand major anesthesia, it can be applied in elderly
patients with an accompanying somatic disease. Photodynamic therapy does not affect
healthy tissues , in contrast with radiotherapy, so it may be applied repeatedly for bulk
tumors or relapses.
One more advantage of the given method is the fine cosmetic result of treatment, so important
for the great number of women and men.
Despite of the obvious positive features, the new technique is not a magic elixir for
all occasions. The success of therapy depends on the stage of disease. The treatment of
extensive tumours with Radachlorin is not radical; in such cases photodynamic therapy can
improve quality of patient’s life, restore the patency of hollow organs (recanalization of
esophagus, rectum, trachea, etc.), but the tumour is not removed completely.
Results
This method was introduced into practice of CSMA Clinic of General surgery under the
direction of professor Privalov V.A.We applied it in more then 100 patients aged from
10 to 93 years with tumours of skin, lower lip, tongue, oral cavity mucous, larynx,
lung, bladder, gastrointestinal tract, genitalias and other localizations.
The irradiation was performed under local or intravenous anaesthesia. At external
irradiations (cancers of skin, lip, and so on) no anaesthesia was required as a rule. For a
day after irradiation patients stayed in black-out rooms without TV to avoid light reactions
of skin and eyes because of some presence of Radachlorin. Then patients were free in respect
to light and TV.
18 patients underwent PDT because of contraindications to traditional treatments (age,
concomitant diseases). 19 patients had recurrent tumours (30 tumors) after standard methods
of treatment (surgery, radiotherapy, chemo- and cryotherapy). In these patients,
photodynamic therapy was carried out not earlier than one month after radiotherapy or drug
therapy. 22 patients entered the hospital with IV stage of disease, 56 patients had I-II
stage tumors, mainly basaliomas. In 12 cases there were primary-multiple tumors.
The PDT efficiency was estimated by visual, endoscopic, radiological, ultrasonic and
cytomorphological researches. Follow-up terms were from 3 to 36 months. Local photodynamic
reaction developed in a few minutes after the beginning of irradiation. By the end of
irradiation, the tumour and surrounding skin became anemic, and "halo" of hyperemia appeared
around. Surface of the tumor became violet or black, because of hemorrhagic necrosis in 2-3
hours. Final results of were estimated as complete tumour regress, partial regress (decrease
of the tumour by 50 %) and absence of effect (decrease of the tumour less than 50 %).
Clinical researches have shown the high efficiency of PDT with Radachlorin for treatment of
cancer of various localizations. Complete regress of the tumor was achieved in 68 %,
partial in 32 % of cases. The absolute (100 %) result was received in treatment of skin
basal cell carcinoma. We managed to improve life quality of 7 incurable patients with
advanced malignancies of different localizations by recanalization of obturated hollow
organs in 5 cases (esophagus, rectum, bronchial tube) and by elimination of inflammatory
complications caused by tumor decay in 2 cases.
