Walter D. Rider

Radiation pneumonitis following large single dose irradiation: A re-evaluation based on absolute dose to lung

Abstract The acute radiation paeumonitis syndrome is a major complication for patients receiving total thoracic irradiation in a large single dose. Previous studies have evaluated the onset of radiation pneumonitis on the basis of radiation doses calculated assuming unit density tissues. In this report, the incidence of radiation pneumonitis is determined as a function of absolute dose to lung. A simple algorithm relating dose correction factor to anterior-posterior patient diameter has been derived using a CT-aided treatment planning system. This algorithm was used to determine, retrospectively, the dose to lung for a group of 303 patients who had been treated with large field irradiation techniques. Of this group, 150 patients had no previous lung disease and had virtually no additional lung irradiation prior or subsequent to their large field treatment. The actuarial incidence of radiation pneaunoniitis versus dose to lung was evaluated using a simplified probit analysis. The resultant best fit sigmoidal complication curve demonstrates the onset of radiation pneumonitis to occur at about 750 red with the 5% actuarial incidence occuring at approximately 820 red. The errors associated with the dose determination procedure as well as the actuarial incidence calculations are considered. The time of onset of radiation paeumonitis occurs between 1 to 7 months after irradiation for 90% of the patients who developed pneumonitis with the peak incidence occurring at 2 to 3 months. No correlation was found between time of onset and the dose to lung over a dose range of 650 to 1250 red.

Results and toxicity of the treatment of anal canal carcinoma by radiation therapy or radiation therapy and chemotherapy.

The results of treating anal canal carcinoma by radical external beam radiation alone (RT) or by combined 5‐fluorouracil, mitomycin C and radiation (FUMIR), were compared in nonrandomized groups of patients treated in a single center. In each treatment regimen, surgery was reserved for those patients with residual carcinoma. The uncorrected 5‐year survival rate in each group was approximately 70%, but primary tumor control was achieved in 93% (28/30) with FUMIR compared to 60% (15/25) treated with RT. Acute hematologic and enterocolic toxicity with uninterrupted external beam radiation courses of 5000 cGy in 4 weeks plus chemotherapy led to the adoption of split‐course treatment. Serious late toxicity requiring surgical intervention occurred in 3 of 25 following RT, and in 5 of 30 following FUMIR. Colostomies were needed as part of treatment for residual carcinoma or for the management of treatment‐related toxicity in 11 of 25 treated by RT and have been required to date in 4 of 30 treated by FUMIR. The improvement in the primary tumor control rate and the reduction in the number of patients requiring colostomy when compared with the results of RT favor combined chemotherapy and radiation as the initial treatment for anal canal carcinoma.

Idiopathic interstitial pneumonia following bone marrow transplantation: the relationship with total body irradiation

Abstract Interstitial pneumonia is a frequent and often fatal complication of allogenic bone marrow transplantation. Thirty to 40 percent of such cases are of unknown etiology and have been labelled as cases of idiopathic interstitial pneumonia. Idiopathic cases are more commonly associated with the use of total body irradiation; their occurrence appears to be independent of immunosupression or graft versus host disease. Evidence is presented from the literature suggesting that the development of idiopathic interstitial pneumonia is related to the absolute absorbed dose of radiation to lung. The similarity of idiopathic pneumonia to radiation paeumonitis seen in a different clinical setting is described.

Half body radiotherapy

“Necessity is the mother of invention and serendipity the handmaiden”. The Toronto philosophy in radiotherapy has, for several decades, been one of large volume irradiation in preference to the more classical teaching of “excisional therapy” using small volumes and high dose. In this respect our pattern of practice has been different and unique. However, it was based on critical retrospective reviews of “patterns of failure.” In most sites where an improvement in survival was demonstrated, this was due to increased volume irradiated rather than increased dose; care was taken to exclude other variables, e.g., stage or grade, which might have been more responsible for any improvement than the therapy itself.

SEMINOMA OF THE TESTIS: RESULTS OF TREATMENT AND PATTERNS OF FAILURE AFTER RADIATION THERAPY

Four hundred and forty-four patients with the histological diagnosis of pure seminoma were treated at The Princess Margaret Hospital between 1958 and 1976. Using the Walter Reed Hospital staging classification, 338 patients (76.1%) were Stage I, 86 (19.4%) were Stage II, and 20 (4.7%) were Stage III. The 5 year actuarial survival rate (5 yr Sa) for all stages was 87%, and for Stages I, II and III: 94%, 74% and 32% respectively. In Stage II the 5-year Sa was significantly worse when palpable abdominal disease was present (62%, vs 87% when it was absent, p less than .02). Prophylactic mediastinal irradiation was not used for patients with Stage II disease. None of 40 Stage II patients without palpable abdominal disease recurred in the non-irradiated mediastinum. Ten of 46 Stage II patients with palpable abdominal disease recurred in the mediastinum; 7 of the 10 were cured with mediastinal irradiation at the time of relapse. Prophylactic mediastinal irradiation appears unnecessary in Stage II patients. The Stage III category includes a subgroup of patients who were curable with radiation therapy:L 5/6 with supradiaphragmatic nodal disease without palpable abdominal or visceral disease were cured. Exploration of new treatment methods appears indicated for the salvage of patients recurring in sites other than the mediastinum or supraclavicular fossa and for patients presenting with visceral disease.

The treatment of glomus tumors in the temporal bone by megavoltage radiation

Forty‐five patients with glomus tumors in the temporal bone region were treated by radiation therapy. Only three patients had recurrence or progression of tumor during the follow‐up period of 3 to 23 years (median, 10 years). No patient died from uncontrolled glomus tumor. The majority of patients noted symptomatic relief after radiation, but objective neurologic deficits usually remained unchanged or showed only partial improvement. The most commonly used radiation dose was 3500 cGy tumor dose delivered in 15 fractions in 3 weeks by a homolateral wedge technique from megavoltage radiation apparatus. This dose is less than that usually recommended for glomus tumors. From these results and from review of the literature, it is suggested that a moderate radiation dose of 3500 cGy in 3 weeks is effective treatment for glomus tumors, even if complete tumor involution does not occur.

Supraglottic laryngeal carcinoma: an analysis of dose-time-volume factors in 410 patients.

Four hundred and ten patients with supraglottic laryngeal carcinoma treated with moderate dose radical radiotherapy with surgery for salvage (RRSS) were analyzed in detail to determine optimal dose-time-volume parameters to be used in the treatment of each stage of supraglottic carcinoma. In the RRSS group 41% are alive and well at 5 years, 38% died of their tumor and 21% of intercurrent disease. Presence or absence of nodal disease has a major impact on survival. Local control is approximately 70% in T1, T2N0 patients and approximately 50% in T3 and T4N0 patients. Seventeen percent of T1 and T2N0 patients failed in the initially negative neck. Ten major complications (2.4%) have been seen. Local control by irradiation was not influenced by dose or field size. Regional control in the initially negative neck was markedly increased with the use of larger irradiation field sizes. Field sizes of less than 7 X 7 cm resulted in an 18% neck failure rate as compared to 3% with larger field sizes (p = 0.00005). This particularly applied to early stage disease. As a result of the use of larger irradiation field sizes giving reduced neck failure rates, improvement in survival has been seen in early stage supraglottic patients. The results are compared with published results. There is no statistically significant dose response curve in any stage of supraglottic cancer over the dose range 1650-2300 ret. Optimal treatment factors for supraglottic cancer are discussed.

Primary radiation therapy for juvenile nasopharyngeal angiofibroma.

Evidence is presented of the effectiveness and relative lack of serious toxicity of external beam megavoltage radiation therapy (RT) as primary treatment for juvenile nasopharyngenl angiofibroma. The importance of careful radiological evaluation of tumor extent prior to irradiation is stressed, and only moderate dose RT is required.

Radical radiation therapy with 5-fluorouracil infusion and mitomycin C for oesophageal squamous carcinoma.

Thirty-five patients with clinically staged non-metastatic squamous carcinoma of the oesophagus were treated with radiation combined with mitomycin C, and 5-fluorouracil (5-FUra) infusion. Twenty patients were planned for a split course regimen 2250-2500 cGy in 10 fractions and chemotherapy. This dose of radiation to be repeated with another course of chemotherapy after 4 weeks rest. Fifteen patients were planned for a single course 4500-5000 cGy in 20 fractions and a single course of chemotherapy. Thirty-one patients are available for a minimum follow-up of one year, 26 patients for a minimum follow-up of 2 years. All 35 patients are included in the survival and local relapse-free analysis. Survival at one year is 47% and at 2 years 28%. The local relapse-free rate at both one and 2 years is 48%. There was an improvement in survival and local relapse-free rate for the single course regimen compared to the split course; 2 years survival 48% versus 12% (p = 0.24) local relapse-free rate 79% versus 27% (p = 0.07). All patients receiving radiation and chemotherapy were compared with historical controls treated by radiation alone. This matching procedure was done independent of knowledge of outcome (two controls were matched/case). Patients were matched for age, sex. TNM stage, and total radiation dose. There was a significant difference in survival p = 0.004 and local relapse-free rate p = 0.05 for patients receiving radiation and chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Lung density as measured by computerized tomography: implications for radiotherapy

Accurate dose calculations for radiotherapy planning require a detailed knowledge of the internal anatomy of the patient both in terms of geometry and density. Computed tomography (CT) is presently the best means of providing these data. Fifty-eight patients who had scans of the thorax for radiotherapy planning were studied. The CT numbers were converted to relative electron densities and average lung densities were obtained for every patient. A linear correlation of lung density with age was found with the mean lung density of 0.35 at an age 5 years and 0.19 at an age of 80. The effect of scanning the patient under full inspiration, full expiration or normal shallow breathing conditions was analyzed. At the age of 5 years the expiration and inspiration average lung densities were 0.36 and 0.20, while at the age of 80 years they were 0.22 and 0.16, respectively. Respiratory volume changes were linearly correlated with changes in relative electron density. Differences in lung density between expiration and inspiration scans were found to demonstrate a similar trend with age as the relationship between vital capacity and age. The dosimetric and the possible clinical implications of lung density measurements for radiotherapy are considered. In particular, dose calculations were performed using scans taken under a number of different respiratory conditions. Doses calculated for a single cobalt-60 beam can differ by more than 25% when comparing a full inspiration scan to a normal breathing scan. A similar comparison for a parallel pair distribution on the lung yields a difference of about 3% while a typical three field technique for treating cancer of the esophagus shows a difference of nearly 10%.