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Biomedical subjects

G A Alexander

Publications and source records attributed to G A Alexander.

41 records · Page 3Linked to original sources
PubMed1978

Twice-a-day treatment in the radiotherapeutic management of malignant mixed tumor of the parotid gland: A case report.

A patient with a 2,300 gm malignant mixed tumor of the parotid gland had recurrence 19 days post surgery. The recurrent mass failed to respond to daily fractions of 200 rad conventional irradiation four times per week and actually increased in size. A superfractionation scheme was substituted, employing twice-a-day 200 rad at 4-5½ hours intervals three times a week for 2½ weeks. At the completion of treatment, there was a 50 percent regression of the recurrent tumor mass and a 100 percent regression two weeks post irradiation. A protocol using a twice-a-day treatment is discussed.

Adenoma, Pleomorphic↗
PubMed1978

Remote afterloading for intracavitary irradiation of cervix carcinoma.

The technique of remote afterloading for intracavitary radiotherapy was developed by Henschke et al 15 years ago, and since then the technique has received wide acceptance, both abroad and in the United States. Here at Howard University, it plays an integral part in the intracavitary portion of the treatment of cervix carcinoma. Most applications are done on an outpatient basis without anesthesia or sedation. This has become possible by dilating the cervical canal painlessly with thin laminaria rods. Spread of the lateral colpostats is accomplished by inflating a Foley balloon secured to the applicator with contrast medias, instead of using the customary gauze packing for increased rectal distance.A single cobalt-60 source of 1 mm diameter and 3 to 7 Curies is used, which can be moved during the treatment to simulate linear sources of different lengths and loading. Our present treatment policy calls for 4,000 rad given to the whole pelvis in 20 fractions of 200 rad three times per week plus eight fractions of 400 rad by the remote afterloading technique given one fraction per week concomtant with the external irradiation. Only 18 patients have been treated to date with minimal adverse tissue reactions. There is only an 18-month maximum follow-up, so survival figures are still pending but all patients so treated are currently living without recurrence.

Carcinoma↗
PubMedDate not supplied

Randomized trial of one versus two adjuvant hyperthermia treatments per week in patients with superficial tumours.

One test for thermotolerance development in a clinical situation is to evaluate the effects of altering the hyperthermia fractionation interval on tumour response to thermoradiotherapy. Between 1983 and 1990 44 evaluable advanced superficial tumours of miscellaneous origin in 41 patients were randomized to receive either once-weekly or twice-weekly external microwave hyperthermia treatments combined with radiation therapy. The mean age of patients was 62 years, and 85% had failed previous therapy. All lesions were less than 8 x 8 x 4 cm (L x W x D) and were heated by external 915 MHz microwaves. The mean radiation dose was 44 +/- 3 Gy (mean +/- SE) in the once-weekly group and 46 +/- 3 Gy in the twice-weekly group (p = 0.64). The mean volume of the lesions heated once weekly was 17 +/- 6 versus 23 +/- 5 cm3 for those heated twice weekly (p = 0.45). Hyperthermia was administered once weekly for 4.6 +/- 0.2 sessions (range 3-7) or twice weekly for 8.1 +/- 0.3 sessions (range 4-10). Thermometry was performed using 3.4 +/- 0.2 catheters and 5.1 +/- 0.6 thermal sensors per tumour in the once-weekly group, and 2.7 +/- 0.2 catheters and 5.8 +/- 0.3 thermal sensors per tumour in the twice-weekly group. Of the 44 evaluable randomized lesions a complete response (CR) at 2 months post-treatment was observed in 59% (13/22) heated once weekly and 55% (12/22) in those heated twice weekly. The prognostic factors predictive of tumour complete response were found by logistic regression analysis to be radiation dose and tumour volume, while the prognostic factors predictive of duration of response (Cox proportional hazards analysis) were median minimum tumour temperature (Tmin), minimum tumour temperature during the first heat treatment (Tmin1) and tumour volume. The duration of local control in lesions with Tmin < or = 39.5 degrees C was 11.7 +/- 1.9 months while for lesions with Tmin > 39.5 degrees C it was 23.0 +/- 4.2 months (p = 0.01). The ED50 was calculated by logistic regression to be 40 Gy (95% CI = 22-54 Gy) for once- and twice-weekly heated lesions. There was not a significant difference in tumour response or duration of response between populations randomized to receive once- versus twice-weekly hyperthermia treatments. There was also no difference in skin reaction rates between once- and twice-weekly hyperthermia treatments, nor could a correlation be found between any thermal parameter and skin reactions.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗