Monte Carlo dosimetry for 125I and 60Co in eye plaque therapy

Monte Carlo calculations of radiation dosimetry using MORSE code are performed for 125I and 60Co point sources in a cylindrical head phantom that simulates the geometry of eye plaque therapy for choroidal melanoma. We obtain the dose variation in the eye at submillimeter intervals over distances as close as 1 mm and up to 2.5 cm from the source. The calculations for 125I are performed for the phantom media of water, protein, and a homogenized protein-water mixture simulating the composition of the eye. Relative dose functions for 125I for these phantom media are fitted to second-degree polynomials. Agreement is found with published results. The relative dose function for 60Co at eye position in the water head phantom is fitted to a third-degree polynomial and compared with that for 60Co at the center of a large water sphere. A boundary effect due to the head phantom-air interface on the dose distribution for 60Co is demonstrated. The dose falloff with distance is faster for the eye geometry compared with the bulk geometry. We also show that the relative dose distributions within the tumor are comparable for 125I and 60Co by comparing their relative dose functions. This result is consistent with the success of clinical trials of large melanoma treatments with 125I plaques.

Effect of misonidazole dose on survival in patients with stage IIIB-IVA squamous cell carcinoma of the uterine cervix: an RTOG randomized trial

Between August 1980 and November 1984, 120 patients with FIGO Stage IIIB or IVA squamous cell carcinoma of the uterine cervix were randomized to receive radiation therapy (RT) (46 Gy pelvis + 10 Gy parametrial boost) followed by intracavitary or external boost to the primary +/- misonidazole (MISO) (400 mg/M2 2-4 hours prior to RT daily, maximum 12 gm/M2). The median at 24-28 hr misonidazole plasma level was 20 micrograms/ml 2-6 hr and 3.5 micrograms/ml. Approximately 60% of the patients on RT + MISO received 100% of expected total Misonidazole dose; peripheral neurologic toxicity was reported for nine patients receiving misonidazole (8 with mild and 1 with moderate paresthesia or pain). Time-dependent regression analyses found that actual cumulative misonidazole dose was not related to duration of survival from start of treatment (p = 0.5). MISO dose expressed as a percent of expected dose was marginally related to increased survival measured from 14 weeks on on study (p = 0.1). No improvement in survival was observed with the addition of misonidazole to RT (64% of the patients on RT alone were alive at 18 months versus 54% of those on RT + MISO).

Complications of combined radical hysterectomy and pelvic radiation

Long-term gastrointestinal (GI) and urinary tract (UT) complications were evaluated in 48 women treated by radical hysterectomy (RH) and pelvic node dissection (PND) and in 25 women who received 5000-5400 rad of external pelvic radiation (RT) after RH-PND. No major complications developed in the surgery-only group, but the 5-year minor GI complication rate was 4% and the 5-year minor UT complication rate was 10%. In 9 patients receiving RT at 200 rad/day, one major GI complication (13%) and one major UT complication (14%) developed. In 16 patients receiving RT at 180 rad/day only minor GI complications (7%) and minor UT complications (13%) developed. The conclusion is that after RH-PND, adjunctive RT delivered at 180 rad/day through four ports results in acceptable, minimal complications.

Comparison of 32P therapy and sequential hemibody irradiation (HBI) for bony metastases as methods of whole body irradiation

We report a retrospective study of 15 patients with prostate carcinoma and diffuse bone metastases treated with sodium 32P for palliation of pain at Downstate Medical Center and Kings County Hospital from 1973 to 1978. The response rates, duration of response, and toxicities are compared with those of other series of patients treated with 32P and with sequential hemibody irradiation. The response rates and duration of response are similar with both modalities ranging from 58 to 95% with a duration of 3.3 to 6 months with 32P and from 75 to 86% with a median duration of 5.5 months with hemibody irradiation. There are significant differences in the patterns of response and in the toxicities of the two treatment methods. Both methods cause significant bone marrow depression. Acute radiation syndrome, radiation pneumonitis, and alopecia are seen with sequential hemibody irradiation and not with 32P, but their incidence can be reduced by careful treatment planning. Hemibody irradiation can provide pain relief within 24 to 48 h, while 32P may produce an initial exacerbation of pain. Lower hemibody irradiation alone is less toxic than either upper hemibody irradiation or 32P treatment.

Depletion of cellular ATP inhibits Na+/H+ antiport in cultured human cells. Modulation of the regulatory effect of intracellular protons on the antiporter activity

The metabolic energy dependency of Na+/H+ exchange activity was investigated in cultured human A431 carcinoma cells and foreskin fibroblasts. Following the activation of Na+/H+ exchange which results from loading cells with Na+ or Li+, depletion of cellular ATP by incubation with metabolic inhibitors causes an inhibition of Na+/H+ exchange activity. This inhibition is reversible and correlates with the extent of the reduction in the ATP pool. On the other hand, reduction of the intracellular pH (pHi) to approximately 6.0-6.2 results in a similar effective activation of Na+/H+ exchange in both control and ATP-depleted cells. Na+/H+ exchange activity in ATP-depleted cells that either have or have not been loaded with Na+ shows a steep dependency on pHi, being essentially abolished above pHi of 6.4-6.5, whereas control cells show a considerable activity also at more alkaline pHi values. Thus, Na+/H+ exchange activity in ATP-depleted cells shows an increased dependency on intracellular protons. These findings suggest that although metabolic energy is not required as a driving force for Na+/H+ antiport, depletion of metabolic energy substrates inhibits the antiporter activity due to a modulation of an intracellular proton-dependent regulatory mechanism.

Adjuvant chemotherapy with adriamycin, cytoxan, and cis-platinum in high-grade carcinoma of the prostate treated with definitive radiotherapy (RTOG pilot 81-12)

In a phase I-II trial, a regimen of Adriamycin, Cytoxan, and cis-Platinum has been tested as an adjuvant to definitive radiotherapy in patients with high-grade (Gleason score 8-10) locally advanced carcinoma of the prostate limited to the pelvis. The patients had no evidence of distant disease, were in good general condition, and had satisfactory cardiac, hepatic, and renal function. Radiation therapy consisted of 4,320-4,500 rad in 23-25 fractions to the pelvis followed by a boost to the prostate to a total of 6,480-7,020 rad in 36-39 treatments. Chemotherapy was scheduled to start 4 weeks after completion of radiotherapy and consisted of 300 mg/m2 of Cyclophosphamide, 30 mg/m2 of Adriamycin, and 50 mg/m2 of cis-Platinum cycles given at 4-week intervals. The primary aim of the study was evaluation of toxicity of the combined regimen. Nine patients were evaluable. No adverse effects of chemotherapy on the incidence and severity of radiation-related toxicity in the pelvis have been observed. Myelosuppression has been significant and has prevented delivery of full doses of chemotherapy. Although planned, no dose escalation was possible. Further reduction of dosage was necessitated in 67% of the patients. Delays in the delivery of chemotherapy were necessary in four patients; the delays ranged from 1 to 14 weeks. Although the regimen had been reported to produce a high rate of response in disseminated disease and has not been associated with an increased incidence of radiation-chemotherapy toxicity in the irradiated pelvis, it does not appear suitable for further testing in an adjuvant setup in patients treated with definitive radiotherapy.

Intracranial metastases from melanoma. Clinical features and treatment by accelerated fractionation

One hundred ninety-four patients with intracranial metastatic melanoma were treated at the M. D. Anderson Hospital between January 1972 and September 1977, using seven different accelerated irradiation regimens. The total tumor dose varied from 3000 to 4800 rad, and the overall treatment time from 1 to 2 weeks. In these patients, whose disease had progressed to brain metastases, freedom from such metastases had decreased logarithmically with time from initial presentation. This suggests a random distribution of progression rates with a mean time of 2.5 years between diagnosis and development of intracranial metastases. Overall, there was no significant improvement in the results from accelerated fractionation in the treatment of intracranial metastases. The result of treatment did not depend on the site of the primary, the number of intracranial metastases, the total dose, or the dose per fraction. There were, however, two subgroups not mutually exclusive, that benefited significantly from the accelerated fractionation: patients having had a complete resection of brain metastases, and those having no detectable extracranial metastases at the time of their treatment for intracranial metastases.

Metastatic melanoma in brain. Rapid treatment or large dose fractions

A subgroup of 59 patients selected on the basis of favorable prognostic factors from a larger group of 194 patients treated for intracranial metastases of melanoma was analyzed with a view to assessing the relative efficacy of different accelerated fractionation regimens. The most effective modification of the previously standard therapy was a shortening of the overall treatment time, although this was also associated with the use of larger doses per fraction. Patients who had brain metastases only at the time of treatment showed a longer survival time than those with coexistent metastases in other organs and survived longer if treated with 10 fractions within 1 week rather than 20 fractions in 2 weeks. The same was found in patients who underwent complete resection of intracranial tumor before irradiation. A complete surgical resection also increased the probability of eliminating intracranial disease, but overall the median survival increased by less than 2 months. It is concluded that a short overall treatment time is more important than large fraction sizes in attempts to improve the treatment of metastatic intracranial melanomas with favorable prognosis.

Complications of combined surgery and radiation therapy for carcinoma of the endometrium

Long-term gastrointestinal (GI) and urinary tract (UT) complications were evaluated in 133 women with carcinoma of the endometrium who were treated by both radiotherapy and hysterectomy. Major complications developed in 8% of patients who received external pelvic radiation but in none with intracavitary radiation. GI complications were more frequent and more severe in patients receiving external pelvic radiation than in those who received only intracavitary radiotherapy, irrespective of the sequence of treatment. UT complications were more frequent with prehysterectomy external radiotherapy (N = 39) than with posthysterectomy external radiotherapy (N = 21).

Iodine-125 irradiation of choroidal melanoma. Clinical experience

Twenty-nine patients with choroidal melanomas were treated with iodine-125 seeds in gold scleral plaques. Iodine-125 emits low energy 25 KeV photons which are attenuated by the side and back of the plaques so that the radiation is "directed" towards the choroidal tumor. The anticipated therapeutic benefits of using a low energy isotope and directional applicators have been realized. There has been a marked reduction in ocular complications in the nine medium and 20 large melanomas so treated. Our complication rate was 34% with a mean follow-up of 38 months. This is a lower complication rate, with longer follow-up, and in larger tumors than that reported with the use of cobalt-60, ruthenium-106 or ion beam. Three patients with large tumors and two patients with medium tumors died of metastasis. This compares favorably to results of similarly sized melanomas treated by enucleation.

Vascular invasion in Stage I carcinoma of the cervix

Vascular invasion was identified as an important prognostic variable for all lesion sizes in 138 patients with Stage I cervical carcinoma. A matched pairs analysis, controlling for lesion size and extracervical spread, showed that vascular invasion was significantly associated with poor outcome. Regression analysis also indicated that vascular invasion contributed prognostic information beyond that available from lesion size and extracervical spread. Studies of adjunctive therapy based on the prognostic variables are recommended.

Split-course versus continuous pelvis irradiation in carcinoma of the uterine cervix: a prospective randomized clinical trial of the Radiation Therapy Oncology Group

In August 1980, the Radiation Therapy Oncology Group (RTOG) completed a prospective randomized clinical trial for the comparison of a split-course versus a standard continuous course of pelvic irradiation for carcinoma of the uterine cervix Stages II-B, III-A, III-B, and IV-A. The split-course consisted of 10 fractions of 250 rad each, 5 times a week, up to 2500 rad followed by a rest period of approximately 2 weeks and then another 2500 rad was given (250 X 10). The continuous course consisted of 30 fractions of 170 rad each, 5 times per week, for a total of 5100 rad. In both groups the external pelvis irradiation was followed by intracavitary brachytherapy in the uterus and vagina, with tandem-colpostat or tandem only, for a dose of 3000 rad at point A for the former, or at 2 cm from the center of the linear source for the latter. In cases where brachytherapy was not possible, a boost of external irradiation with reduced field, with a dose of 1600 rad (200 X 8) was advised. Three hundred and one patients were registered, of which 287 are currently evaluable. No differences between the treatments were detected for the following study end-points: treatment tolerance in terms of acute normal tissue reactions and completion of therapy, tumor control in the pelvis, severe late normal tissue reactions, and survival. In the entire study population the estimated tumor control in the pelvis at two years after initiation of therapy was: 81% for Stage II-B, 67% for III-A, 53% for Stage III-B, and 32% for Stage IV-A. The estimated two-year survival was: 70% for Stage II-B, 58% for III-A, 46% for III-B, and 23% for IV-A.

Prognostic factors in cervical carcinoma: implications in staging and management

Individualization of treatment using judicious combinations of external and intracavitary irradiation remains the cornerstone of the radiation management of carcinoma of the cervix. The inherent propensity of this cancer to either confine itself to the pelvis or else spread in a systematic and predictable manner through lymphatic channels has facilitated its therapeutic control. The treatment of most early invasive cervical carcinomas is equally advantageous using either intracavitary radium or surgery. However, certain Stage I patients have morphologic and histologic characteristics that militate against tumor control. Factors such as tumor size, depth of invasion, vascular infiltration, uterine extension, and barrel-shaped presentation affect the course of the disease and survival. A clinical-pathologic staging for cervical carcinoma incorporating the above mentioned factors into the current clinical FIGO staging system has been suggested. It aims to facilitate the recognition of those early tumors that require additional external radiotherapy. A description of the role of surgery, intracavitary and external radiation, and their combinations is included. In advanced carcinoma of the cervix, failure can be attributed to either large tumors containing cores of hypoxic cells resistant to conventional radiation therapy or to uncontrolled subclinical disease in the lymphatics at or near the border of the irradiated area. Radiotherapy combined with surgery, oxygen enhancers, infusion chemotherapy, and large particle high LET radiation has been implemented to increase local control; for distal failures, extended field irradiation of paraaortic nodes has been found to be technically feasible and well tolerated and is being studied for its effects on increased survival. The rationale for newer treatment procedures, including preliminary results and their complications, is discussed.

Irradiation of choroidal melanoma with iodine 125 ophthalmic plaque

Radioactive iodine 125 is a low-energy gamma isotope with physical characteristics suitable for irradiation of intraocular tumors. Metal ophthalmic applicators have been designed to shield vital ocular structures while allowing irradiation of the tumor. We compared the radiation effects of iodine 125 and cobalt 60. The Greene melanoma was transplanted into the suprachoroidal space of rabbits. The tumor then grew as an intraocular mass, was irradiated, and was followed up for two months before enucleation. Histopathologic examination defined the extent of the radiation damage to the tumor and other ocular structures from the iodine 125 and from the cobalt 60. The eye irradiated with iodine 125 suffered minimal radiation damage, whereas the tumor was sterilized. The eye irradiated with cobalt 60 showed substantial radiation damage, and the melanoma was incompletely treated. Our results support the use of iodine 125 in treating intraocular tumors. More research is needed as to optimum total dose and dose rate.

Radiotherapy of choroidal melanoma with iodine-125

The low-energy radioactive source iodine-125 is ideal for the irradiation of an intraocular tumor tumor such as a choroidal melanoma. The energy (28 kev) of iodine-125 should be sufficient to allow sterilization of tumors as high as 10 mm. However, shielding of 18-kev photons can be achieved with thin metal (eg, gold) plaques. Thse eye plaques can be individually designed for each eye tumor, depending on its size, shape, and location. This paper deals with the basic considerations and preliminary observations that have lead us to the adoption of iodine-125 as the sole source for the radiation treatment of all intraocular tumors.

Radiation therapy of choroidal melanoma

During the past 8 years, 32 patients with melanoma of the choroid have been treated with cobalt-60 ophthalmic applicators. Excluding three patients lost to follow-up, 24 patients who have now been observed for at least 3 years after treatment form the subject of this study. Each application but two delivered 8,500 to 10,000 rads to the tumour apex. A second application was performed in large tumours showing a poor response to the initial plaque treatment. The factors affecting results include age of the patient, tumour size, total dose delivered, and dose rate. Three out of seventeen patients with tumour diameters greater than 12 mm died of their disease with pulmonary and/or liver metastasis. Three eyes required enucleation and no residual tumour was found in two specimens. Three patients, average age 76 years, died from causes other than melanoma. An 83 per cent relative survival, excluding the three patients lost to follow-up, compares favourably with enucleation. The low incidence of metastasis after radiotherapy suggests augmentation and/or continuation of the host's immune response. Low energy radiation using Iodine-125, with its unusual protective characteristics is ideal for treatment of choroidal melanoma.

Supportive therapy in radiation oncology

Measures for supportive care of the radiation therapy patient are presented. These include emotional support prior to and during the course of therapy facilitated by a written interview that allows the radiation oncologist to be a supportive communicator of realistic information. A discussion is made of the support of body tissues affected by combination radiation and chemotherapy. These tissues usually include skin, oral, esophageal and intestinal mucosa, and teeth. Means of maintaining nutritional support following weight loss of patients during therapy are described.

Renal metastases simulating Kaposi sarcoma. Radionuclide scanning, an aid in diagnosis and treatment planning

A case of renal cutaneous metastases simulated Kaposi sarcoma and the condition was misdiagnosed as Kaposi sarcoma. A new technique was employed using the isotope technetium 99m as the compound sodium pertechnetate Tc 99m for the diagnosis and evaluation of the extent of Kaposi sarcoma. The failure to demonstrate a positive isotope scan in our case was a clue to the incorrect diagnosis of Kaposi sarcoma.

A clinical and follow-up study of right and left bundle branch block

The experience with bundle branch block at the USAF School of Aerospace Medicine was reviewed. The clinical and follow-up status was evaluated in 394 subjects with right bundle branch block (RBBB) and 125 subjects with left bundle branch block (LBBB). The majority of subjects were asymptomatic at the time of bundle branch block diagnosis. The subjects were divided into subfroups based on electrocardiographic (EEG) findings to determine if any one subfroup was at higher risk for initial or follow-up morbidity of cardiobascular disease or follow-up mortality. At initial diagnosis and clinical evaluation, 94% of RBBB and 89% of LBBB subjects had no evidence of cardiobascular disease. In the RBBB group, 3 and 2% had cornary heart disease and hypertension, respectively; in LBBB subjects, 9 and 7% had cornary heart disease and hypertension, respectively. No one ECG subfroup in either the RBBB or LBBB group had a higher incidence of cardiobascular disease. Complete follow-up information was available in 94% of the RBBB subgroup subjects and 91% of the LBBB group. In the follow-up period, new cases of coronary heart disease and hypertension occurred in 6% of the RBBB group and 5 and 8%, respectively, in the LBBB group. Fourteen (4%) RBBB and nine (8%) LBBB subjects died during the follow-up period. No differences for follow-up groups. Progressive electrical dysfunction in the form of complete heart block occurred in one subject each absence, and degree of associated cardiobascular disease. Furthermore, within the age limits of the present aeromedical implications of bundle block are discussed.