Carolyn R. Freeman

Unilateral radiation nephropathy--the long-term significance.

Eighteen patients with gastrointestinal and retroperitoneal non-Hodgkins lymphoma received abdominal radiotherapy as their primary treatment. Each patient received a total tumor dose of 2200 to 4500 cGy in 5 to 9 weeks to the whole or half of one kidney. Nine patients developed unilateral radiation nephropathy demonstrable on post-treatment evaluation with 99m Tc glucoheptonate blood flow, delayed static scan, and an I-131 radio-hippurate renal perfusion study. The tests were periodically repeated over periods ranging from 5 to 8 years. Six patients with nephropathy and 4 patients without nephropathy were followed 5 years or longer. The minimum nephro-pathogenic irradiation dose was 2200 cGy delivered in 59 days. The incidence of nephropathy is higher with increase in the total dose. Short term recovery in function was observed in 3 patients and long-term complete recovery was observed in one patient. Atrophic renal change was irreversible and progressive in 3 patients over a 6 to 7 year follow-up period. In this group of patients, an abnormal creatinine clearance and serum beta-2 microglobulin level was indicative of vascular damage. Elevated arterial blood pressure was seen in 5 patients. All were controlled medically, without nephrectomy. There was no other clinically significant problem resulting from the unilateral nephropathy in this group of patients.

Interstitial pneumonitis following total body irradiation for bone marrow transplantation using two different dose rates

A total of 22 patients with leukemia (10 ALL, 11 AML, 1 CML) have undergone allogeneic bone marrow transplantation (BMT) by the Quebec Co-operative Group for Marrow Transplantation from 1980 to 1982. All patients received 900 cGy total body irradiation (TBI), in a single fraction, on the day preceding BMT. The first 11 patients were treated on a cobalt unit at a constant dose rate of 4.7 to 6.3 cGy/min. Six of these patients developed interstitial pneumonitis (IP). The clinical course of three patients, two with idiopathic and one with drug-induced pneumonitis, was mild and recovery was complete in all. The other three patients developed severe infectious IP and two died. The next 11 patients were treated with a sweeping beam technique on a 4 MV linear accelerator delivering a total tumor dose of 900 cGy at an average dose rate of 6.0 to 6.5 cGy/min but an instantaneous dose rate of 21.0 to 23.5 cGy/min. Eight patients developed severe IP. Five of these were idiopathic and four died. Three were infectious and all died. The fatality of interstitial pneumonitis appeared to be greater in the group treated with the sweeping beam technique.

Retinoblastoma: the case for radiotherapy and for adjuvant chemotherapy.

The results of treatment for 39 consecutive children with retinoblastoma that was diagnosed between 1951 and 1978 were analyzed. Failure to achieve local control within the eye and the development of metastatic disease occurred in seven patients. These patients are considered individually. Delay in diagnosis, older age at presentation, and extraocular extension of disease at diagnosis were associated with treatment failure and were closely interrelated. Modified radiotherapy techniques using wider fields may prevent failure even in those cases diagnosed late and in those with extraocular extension. Indications for intrathecal and systemic chemotherapy in this disease are discussed.

Physical aspects of the angle-β concept in electron arc therapy

A technique for the determination of treatment parameters that are required to achieve a desired depth dose distribution in electron arc therapy is discussed and a method for calculating isodose distributions is presented. Both the treatment technique and the dose calculation method rely on the angle beta concept, which uniquely describes the dependence of the radial percentage depth doses in electron arc therapy on the nominal field width, isocenter depth, and virtual source-axis distance. The angle beta concept is discussed in detail and the electron pseudo-arc therapy technique used at McGill is described. Also presented is the method used to achieve dose homogeneity in target volumes treated with the pseudo-arc technique.

Determination of secondary collimator shape in electron arc therapy

The characteristic angle- beta concept in electron arc therapy of non-cylindrical target volumes is applied in determining the required shape of the arced electron field to yield a uniform dose distribution inside the target volume. The empirical relationships derived for this purpose from the angle- beta concept are valid for all field widths and thus offer an improvement over the currently known empirical relationships which were derived as small-field-width approximations. The validity of the determination of field shapes in electron arc therapy with the empirical relationships based on the angle- beta concept is confirmed by measurements of dose distributions in a spherical phantom.

Biochemical failure as single abnormality in patients with prostate cancer following radical treatment with external radiotherapy: follow-up without immediate treatment

INTRODUCTIONnBiochemical failure has been defined as 3 consecutive increases in PSA following curative treatment of prostate cancer. The appropriate management in such cases is controversial. The most usual treatment has been early introduction of hormones. Such patients will live for many years and hormone therapy causes important secondary effects and increases costs. The guideline in our Department of Radiotherapy has been to follow up, with no initial therapy, cases with low PSA and short PSA doubling time. The present study reports this experience.nnnMATERIALS AND METHODSn528 patients with localized prostate cancer were treated by radical approach between 1992 and 1999, with external radiotherapy, with or without adjuvant hormone therapy. After a median follow-up of 77 months, there were 207 (39%) cases with biochemical failure, 78 of which were followed without therapy after the identification of biochemical failure. All of them were asymptomatic patients and had negative radiographic examinations or did not have imaging exams requested since they presented a favorable outcome. The follow-up included at least 2 annual visits with physical examination and PSA.nnnRESULTSnOf the 78 patients with biochemical failure followed without initial therapy, 7 died from other causes than prostate cancer and the remaining 71 cases were alive and asymptomatic in the last follow-up. Prognostic factors previous to radiotherapy such as stage and Gleason score were not considered when deciding for follow-up without initial therapy in these cases. The most significant aspects considered for this decision were low PSA value (median PSA on the last visit for the 78 cases was only 3.9 ng/mL) and a slow PSA doubling time (in the present experience the median PSA doubling time was 22.5 months).nnnCONCLUSIONnThere seems to be space for expectant management, without initial hormone therapy, in patients with prostate cancer who present biochemical failure and are asymptomatic after radical external radiotherapy. This decision is important, since early introduction of hormones brings late effects and is expensive. Prospective and randomized studies are required to define this issue.