Kenneth H. Luk

Medulloblastoma: treatment results and effect on normal tissues.

Thirty‐three children under age 20 with medulloblastoma, treated between 1962 and 1976, at the University of California and the Claire Zellerbach Saroni Tumor Institute of Mount Zion Hospital, San Francisco, were retrospectively studied. A relationship between dose and local control rate was suggested by an improved five‐year survival in those patients receiving doses greater than 5000 rads to the posterior fossa. The posterior fossa, either alone or with the spinal cord, was the most frequent site of failure. Results of re‐irradiation for failure were encouraging and no significant complications were noted. A study of the effects of craniospinal irradiation on the hematopoietic and immune system demonstrated a marked decrease in the peripheral lymphocyte population at the completion of therapy and suggested a functional impairment of the remaining lymphocytes. Other side effects of irradiation included suppression of the hypothalamic‐pituitary axis and one instance of brain necrosis. Current treatment policy and proposals for future modifications are discussed. Cancer 43:1014–1020, 1979.

The interaction of radiation and cis-diamminedichloroplatinum (II) in intestinal crypt cells

Abstract The effect of radiation and cis-platinum in combination was studied in the intestinal crypt cell survival system of the LAF 1 mouse. The drug LD5060 was 22 mg/kg and the maximum tolerated dose (MTD) (LD 01 ) was 13 mg/kg. That dose caused 80% cell kill when given either 3 hrs after or 2 hrs before a dose of 1100 rad. When the MTD was given from −48 to +48 hrs relative to a dose of 1110 rad, survival fluctuated with minima at −12 hrs, 0 and +12 hrs. A radiation survival curve determined 2 hrs after an MTD drug dose was parallel to the control, but shifted to lower doses due to cell kill. The extrapolated D Q was 280 rad, but the split dose survival ratio was only 1.3 compared to a control value of 7 at the same survival level. A repeat experiment with B 6 AF 1 mice yielded a survival ratio of 3 vs 6 for controls. Cis-platinum may reduce repair of radiation injury, as well as kill intestinal crypt cells.

Design and thermometry of an intracavitary microwave applicator suitable for treatment of some vaginal and rectal cancers

The construction of a modified coaxial cable as an intracavitary microwave applicator suitable for use in some vaginal and rectal cancers is presented. Thermometry was performed for microwave frequencies of 300, 400, 650, and 915 MHz. Temperature profiles in tissue phantoms were obtained with non-perturbing temperature probes and thermography, and the data were compared with those obtained in dogs. The temperature profiles were dependent on the frequency of the microwaves and the insertion depth of the applicator. In addition, an acrylic cylindrical spacer external to the applicator also altered the heating pattern. Therefore, with proper combinations of frequency, insertion depth and spacer, the applicator can be used for heating tumors in some clinical situations.

Adenocarcinoma of the retroperitoneal ascending and descending colon: Sites of initial dissemination and clinical patterns of recurrence following surgery alone

One hundred twenty-seven patients with previously untreated primary carcinomas of proximal, retroperitoneal large bowel were retrospectively analyzed. Sites of involvement in 33 patients with surgically incurable (disseminated) disease were analyzed to define patterns of initial spread. Ninety-four patients were analyzed following attempted curative resection to determine anatomical distribution of initial clinical recurrences. Thirty-one patients recurred (33%). Twenty-four of these patients (77.5%) demonstrated an initial pattern of relapse clinically confined to the abdomen and retroperitoneum. Analysis was performed to identify factors of prognostic significance. Implications for adjuvant therapy are discussed.

Combined radiation and hyperthermia: Comparison of two treatment schedules based on data from a registry established by the Radiation Therapy Oncology Group (RTOG)

A registry established by the Radiation Therapy Oncology Group provides data for assessing the impact of clinical heating in a set of non-randomized patients treated with hyperthermia in participating member institutions from 1/77 to 6/81. This analysis focuses on tumor response when localized hyperthermia is produced by microwave and applied pursuant to two distinctly different treatment schedules. Hyperthermia treatments were biweekly and combined with daily radiation treatments in one patient group, and combined with biweekly radiation treatment in another. Sample X consists of 65 patients who received a course of therapy using combined hyperthermia and radiation in consecutive treatment sessions each separated by at least 48 hours, but no more than 96 hours. Sample Y consists of 34 patients who received further radiation after the start of a course of combined therapy--either between or at the end of a series of combined treatment sessions. The average length of heat treatment was 72 minutes for Sample X and 32 minutes for Sample Y patients. None of the patients received concurrent chemotherapy; all received between 3 and 13 hyperthermia treatments; all had superficial, measurable tumors. On the average, Sample X patients received 704 total minutes of heat compared to Sample Y patients who received 233 total minutes of heat. Total tumor radiation doses ranged from 17.0 Gy to 44.0 Gy among Sample X patients with 92.3% receiving radiation at either 3 Gy or 4 Gy per fraction. In Sample Y the range for total tumor dose was 16.0 Gy to 70.2 Gy with 73.4% of the patients receiving radiation at 2.5 Gy or less per fraction. Generally, the two treatment schedules achieved similar levels of tumor response. Among treated tumors in Sample X and Sample Y, complete regression rates were 52.4 and 61.8%, respectively, and partial regression rates were 16.9 and 14.7%. Adenocarcinoma and squamous cell carcinoma in both samples responded well to these combined treatments. Only in Sample X was there a statistically significant trend of decreasing complete regression rate when the treated tumor sizes increased. Best responses to treatment generally occurred between 28 and 84 days after completion of the combined therapy course. There were no differences between the two samples with respect to median days to best response or response duration. Blister, ulcer or wet desquamation were reported in 47.7% of Sample X as the maximum skin reaction. In contrast, only 20.6% of Sample Y had these complications.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma of the cecum: Natural history and clinical patterns of recurrence following radical surgery

One hundred and forty-three patients with previously untreated primary adenocarcinomas of the cecum were analyzed. Fifty-three patients manifesting disseminated disease at diagnosis were analyzed to define mechanisms of disease spread. Ninety patients were analyzed following attempted curative resection to determine anatomical distribution of initial clinical recurrences. Twenty-eight patients recurred (31%), of whom 9 underwent a second laparotomy. Nineteen of the 28 patients who recurred (68%) demonstrated an initial pattern of relapse clinically confined to the abdomen, liver, and retroperitoneum. Analysis was performed to determine the influence of stage and grade of the primary tumor on prognosis. Implications for adjuvant therapy are discussed.

Locate: An application of computed tomography in radiation therapy treatment planning with emphasis on tumor localization

Computed tomography can provide precise information for radiation therapy treatment planning. However, inaccuracies in radiation field design may occur when the radiation oncologist attempts to transfer information about tumor location from the transverse plane of the CT scan to the longitudinal plane of the simulation film. This report describes a new computer program, LOCATE, which addresses this problem. The program uses operator generated information from the cross sectional CT images to draw an outline of tumor on AP and lateral longitudinal scanned projection radiographs. The resultant images are useful because they are in the same plane as radiographs obtained on a therapy simulator. The impact of LOCATE on radiation treatment planning for 26 patients is discussed along with several cases in which LOCATE was particularly helpful.

Radiation therapy and hyperthermia in the treatment of superficial lesions: preliminary analysis: treatment efficacy, and reaction of skin, tissues subcutaneous.

SUPERFICIAL AND MEASURABLE TUMORS WERE treated with hyperthermia and radiation therapy according to RTOG protocol 78–06. This study focuses on a subset of patients who were heated with microwaves. Eighty patients representing 88 lesions were treated between 1978 and 1981 with a schedule which allowed 48–96 hours to elapse between treatment sessions. The mean value of the average temperatures for individual lesions was 42.3°C. The mean total radiation dose was 33.95 Gy.Skin reaction was examined in terms of the maximum score reported, using a modified Fowler scale. Erythema, the most common finding, was reported as the maximum skin reaction in 24% of the cases. Ulcerations and blisters occurred with frequencies of 18% and 7%, respectively. No reaction or desquamation was reported in 19% and 17% of the cases.Complete regression was noted in 48% of the treated lesions, partial regression in 17%, and no change in 24%. Twenty-five percent of the patients enjoyed sustained response for greater than 180 days.Refinement of hyperthermia treatment equipment and technique may result in less normal tissue reaction and improved clinical responses. In view of the encouraging initial results, we recommend aggressive pursuit of hyperthermia as a new treatment modality.

Hyperbaric oxygen after radiation and its effect on the production of radiation myelitis

Abstract A 1-cm length of rat spinal cord was exposed to 250 kVp X-rays. A single dose of 3500 rad or 5000 rad was delivered in 10 fractions over 12 days. Immediately following each fraction, the rats were exposed to hyperbaric oxygen (OHP) (3 ATA) for a period of 1 hr. Hyperbaric oxygen given after radiation increased the incidence of radiation myelitis as compared to X-ray only, but did not change the time required for symptoms to develop. The authors suggest that OHP may interfere with the early repair of cellular radiation damage when the OHP is applied immediately following irradiation.

PATTERNS OF CARE IN RADIATION THERAPY OF ADENOCARCINOMA OF THE ENDOMETRIUM

In 1974 the Patterns of Care Study began investigating radiation therapy of endometrial cancers in the United States. This endeavor required development of a methodology to survey the care of patients who had similar disease and who were treated at various institutions. Analysis of 919 questionnaires revealed a substantial difference nationwide in treatment approaches to this site. Outcome studies and ongoing research projects, combined with this survey of Patterns of Care, can provide a sound base for educational efforts to improve patient care.