Porphyrin fluorescence and photosensitization in head and neck cancer.

Indistinct margin demarcation and autofluorescence are problems in fluorescence delineation of porphyrin-containing head and neck squamous cell cancer (HNSCC). We studied the time course and in vivo localization of porphyrin fluorescence in a squamous cell cancer hamster model and in human HNSCC. After intravenous injection, a gradient in fluorescence intensity developed rapidly until tumors fluoresced above a lower-intensity mucosal background. Hamster tumor and ulcerated HNSCC without porphyrin injection demonstrated autofluorescence grossly indistinguishable from fluorescence in porphyrin-injected tumors. However, fluorescence microscopy revealed autofluorescence to be a surface phenomenon and showed injected porphyrin localized in tumor stroma. We conclude that autofluorescence must be considered when interpreting porphyrin fluorescence. In addition, empirically designed photodynamic therapy can be effective in selected HNSCC. Data from animal experiments provide useful guidelines for the delivery of this therapy.

Photodynamic therapy in the treatment of squamous cell carcinoma of the head and neck.

Photodynamic therapy is an experimental modality for tumor treatment based on the combined action of the tumor-localizing agent, ie, hematoporphyrin derivative, and red light. From 1985 through 1989, 26 patients were treated using hematoporphyrin-derived drugs and 630-nm light delivered by a tunable dye laser. All patients had biopsy-proved squamous cell carcinoma of the head and neck, and they had either failed the traditional treatment modalities or refused conventional therapies. Histological complete responses were achieved in 20 (77%) of 26 patients and partial responses in 5 (19%) of 26 patients for periods up to 48 months. Only minimal toxic reaction was noted in the group. As a guide to treatment planning for a patient group with large tumors, we used an optical dosimetry model based on tissue optics. The rate of complete responses to this treatment was 8 (73%) of 11. Our data indicate that photodynamic therapy is capable of inducing significant clinical and histological responses in the majority of those treated, and in some patients a prolonged response is produced. In certain select head and neck malignancies, photodynamic therapy has an important role as a treatment modality.

Removal of benign intraoral masses using the CO2 laser.

Benign soft tissue lesions of the mouth can be removed using the CO2 laser. This type of laser surgery is faster and offers less postoperative complication as compared with conventional surgery and electrosurgery. Presently, the CO2 laser can be used for intraoral biopsy of benign masses, gingivectomies, and frenectomies.

Clinical experiences with photodynamic therapy for recurrent malignancies of the lower female genital tract.

Photodynamic therapy (PDT) with Photofrin II was administered over a 7-year period to 17 patients with recurrent carcinoma in situ (CIS) of the vulva, vagina, and perianum. Ten patients were treated two or three times after average intervening periods of 23 and 19 months, respectively. A histologically complete response at 3 months after the PDT session was achieved for 27 of 38 (71%) anatomic sites. Ten patients of this group remain free of recurrences for periods of 2-7 years. Condylomata acuminata associated with CIS in 16 of 17 patients recurred rapidly in 7 patients after PDT. Only short-term palliative results were achieved for 4 patients treated with PDT for invasive carcinoma. Fifteen patients experienced a significant skin reaction to direct sunlight during a 7-week period post-PDT.

Lasers in gynecology.

Lasers are used in gynecology for excising lesions of the cervix, vagina, and vulva. The carbon dioxide laser is most commonly used, offering precision, minimal blood loss, and prevention of strictures. Preoperative diagnostic evaluation and visualization of the lesion is essential. Endoscopic use of the neodymium:yttrium-aluminum-garnet laser through the hysteroscope for excessive uterine bleeding, and laparoscopic use of the CO2 laser for ablation of endometriosis and associated adhesions have been successful. Photoradiation with an argon tunable dye laser has been used to destroy cancer cells containing a hematoporphyrin derivative. Because special skills are required in laser use, criteria establishing qualifications of users have been developed and are recommended for use.

Safety measures in gynecological laser surgery.

The advantages of the laser have been extolled in the literature but, in contrast, there is a paucity of information on the hazards involved in its surgical use. Recognition and prevention of risks is a mandatory requirement. The experience by encounter is described with counsel as to the prerequisite of taking precautionary measures prior to and during any operative procedure. Although safety features are incorporated in the equipment by the manufacturer, failure to peruse the operating manual has led to unnecessary errors in application and control. The operator and assisting personnel must be disciplined to concentrate on every use of the laser. Granting professionals surgical laser privileges with minimal training is an error in administration. A safety officer should be designated from the nursing or technician staff who will be responsible for knowing all the federal rules and regulations, setting up equipment, and constantly exercising safety surveillance during a laser surgical procedure.

Photodynamic therapy for treatment of malignant cutaneous lesions.

Photodynamic therapy, employing either hematoporphyrin derivative or dihematoporphyrin ether as the photosensitizer and an argon-pumped tunable dye laser as the activating light source, was used to treat ten patients who had primary or recurrent basal or squamous cell carcinoma or infiltrating ductal cell carcinoma lesions metastatic to the skin. Of the 155 sites that were treated, various degrees of edema, erythema, and necrosis, sometimes accompanied by blistering, were evident in all areas within 24 to 48 hours of light treatment. While our follow-up periods are short, four patients are free of disease at eight months or more posttreatment, two patients have had recurrent and/or persistent disease within four months, and four patients died within nine months from metastatic disease or unrelated disorders. Continued investigation into the use of photodynamic therapy for treatment of malignant lesions appears warranted, based on these preliminary clinical results.

Radionuclide assessment of right and left ventricular function during bicycle exercise in young patients with cystic fibrosis.

Right and left ventricular performance during exercise was evaluated in 31 patients with cystic fibrosis using equilibrium radionuclide cineangiography. There were 21 males and 10 females (mean age 17, range 10.4 to 34.9 yr) with a wide range of clinical involvement. Thirteen patients had arterial desaturation at rest and an additional 4 became desaturated with exercise. Nine patients (29%) were unable to increase their right ventricular ejection fraction more than 5% during exercise. Left ventricular ejection fraction at rest was normal (greater than 55%) in all but 2, and with exercise, performance was impaired in 9 (29%). No relationship was found between resting or exercise radionuclide ejection fraction, M-mode echocardiography or pulmonary function studies. This study suggests that both right and left ventricular dysfunction may occur during stress in patients with cystic fibrosis without other conventional clinical signs or symptoms. Radionuclide cardiac angiography appears to be a safe method of assessing cardiac response to exercise in patients with chronic lung disease, and may be useful in evaluating therapeutic interventions.