• Results and Discussion

    Median age at the start of radiation therapy was 43 years (range 19-64 years). Twenty-eight patients were males (44%) and 35 patients were females (56%). Fourteen patients were treated with radiation therapy alone. Forty nine patients were treated with a combination of radiation therapy and surgery of whom 40 patients had one, five patients had two and one patient had three operations before radiation therapy. Two patients underwent surgery after radiation therapy. One patient had radiation therapy in between two pituitary operations. Median follow-up time in the radiation therapy group was 84 months (range 18 – 250 months).
    Total radiation therapy dose ranged from 45 to 55.5 Gy (median dose 49.5 Gy). Median overall treatment time was 36 days (range 31-54 days). The daily fraction size varied from 1.8 to 2.1 Gy in 55 patients (median dose 1.8 Gy). In six patients the radiation therapy course was initiated with gradually increasing doses between 1 Gy and 2 Gy daily. From two patients only the total dose was known, but we assume that they were treated with an increasing daily dose as just mentioned, which was standard between 1967 and 1974. The most common dose and fractionation scheme used was 45 Gy in 1.8 Gy daily fractions (n = 27; 43%), mainly performed in the time period 1985-1998. Fifty Gy in 2 Gy daily fractions, mainly performed in the time period 1974-1984 was administered to 20 patients (32%). Eleven patients received a total dose greater than 50 Gy; ten of them had been irradiated before 1981. In all patients all radiation treatment fields were given every treatment day.
    In the time-period 1969-1978 the betatron with energy 18 MV HVD 17 mm PB was used in 13 patients; a five- or seven-field technique was used with standard field sizes of 4 by 4 cm. Three patients were treated with a cobalt source, energy 1.25 MV HVD 11 mm PB, a four-field technique was used twice and a combination of an opposed lateral field technique followed by a three-field technique was used once. Treatment fields varied between 4 and 5 cm in lateral or cranio-caudal dimension. From 1979 onwards patients were treated on linear accelerators with 4MV photons (n = 2), 6 MV photons (n = 20), 8 MV photons (n = 24) and 10 MV photons (n = 1). A two-field opposed lateral technique was used in seven patients, a three-field technique in 12 patients, a rotation technique in one patient, a five-field technique in 11 patients, a six-field technique in one patient and a combination of above mentioned techniques in 15 patients; most of the time a combination of opposed lateral fields followed by a five-field (n = 11) or a three-field technique (n = 3). In the time period 1979-1989 the treatment plan was normalised on the encompassing isodose, afterwards according to ICRU11. Treatment-field dimensions varied between 3 and 6 cm.
    RON was diagnosed in two of the 63 irradiated patients (3.2%, 95% CI: 0.3 – 11.2%). In one patient RON was unilateral (case 1) and in the other patient RON was bilateral (case 2).

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