[Radiation effects in the left kidney after irradiation of the spleen]

Abstract

Background: An important component of treatment of malignant lymphoma is the radiotherapy. If the spleen has to be included in the irradiation field, the left kidney has to be considered as a risk organ.

Patients and method: In 25 patients, splenic pedicle or spleen was included in the irradiation field. These patients were followed up at 6-monthly intervals clinically and by renal scintigram. For 21 out of 25 patients, a volume-dose-histogram of the kidneys was made.

Results: A decreased uptake of activity by the left kidney was found in the static renal scintigram of 13 out of the 25 patients and was seen 6 months to 1 year after radiotherapy for the first time at a moderate intensity. The decreased uptake improved in 1 patient, but was progressive in 8 patients until a storage defect or a shrinking of the whole left kidney appeared. The volume-dose-histogram showed that a decreased uptake was seen in the upper half or whole left kidney respectively if at least 40% of the volume or the whole organ was irradiated with at least 20 Gy. 40% of the volume of the left kidney were exposed to at least 20 Gy in only for 3 out of the 12 patients with no decreased uptake. By means of the renal sequence scintigram a reduced function of the left kidney was determined for 11 out of 13 patients. The functional contribution of the left kidney deteriorated to 16 to 37% of the total function of the 2 kidneys. One patient developed a hypertension 1 1/2 years after radiotherapy; all other patients showed no clinical symptoms. Retention of substances in blood was not observed.

Conclusions: The static renal scintigram enables defined radiation-induced lesions of parenchyma of the left kidney to be determined after irradiation of the splenic pedicle or spleen. The changes are predominantly subclinical but possible long-term effects are unknown. In the treatment planning all possibilities should be used to minimize the irradiation volume of the left kidney. Furthermore, all patients should be followed up at regular intervals on a long-term basis.