Radiation is often used immediately after surgery (postOp radiation) some studies are noted below:

 

Immediate postoperative radiotherapy in residual nonfunctioning pituitary adenoma: Beneficial effect on local control without additional negative impact on pituitary function and life expectancy

van den Bergh IJROBP 2007;67:863

Purpose: To demonstrate the benefit of immediate postoperative radiotherapy in residual nonfunctioning pituitary adenoma (NFA) in perspective to the need for hormonal substitution and life expectancy.

Methods and Materials: Retrospective cohort analysis of 122 patients, operated for NFA between 1979 and 1998. Recurrence was defined as regrowth on computed tomography or magnetic resonance imaging. The occurrence of hormonal deficiencies was defined as the starting date of hormonal substitution therapy.

Results: Seventy-six patients had residual NFA after surgery and received immediate postoperative radiotherapy (Group 1); three patients developed a recurrence, resulting in a 95% local control rate at 10 years. Twenty-eight patients had residual NFA after surgery, but were followed by a wait-and-see policy (Group 2). Sixteen developed a recurrence, resulting in a local control rate of 49% at 5 years and 22% at 10 years (p < 0.001 compared with Group 1). There were no differences between Group 1 and 2 regarding the need for substitution with thyroid hormone, glucocorticoids, and sex hormones before first surgery, directly after surgery and at end of follow-up. There were no differences in hormone substitution free survival between Group 1 and Group 2 during the study period after first surgery. Life expectancy was similar in Group 1 and 2, and their median life expectancy did not differ from median life expectancy in the general population.

Conclusions: Immediate postoperative radiotherapy provides a marked improvement of local control among patients with residual NFA compared with surgery alone, without an additional deleterious effect on pituitary function and life expectancy.

In the present series of NFA patients, excellent local control (95% at 10 years) was achieved when immediate postoperative radiotherapy was applied in case of residual tumor. In comparison, local control was only 49% at 5 years and 22% at 10 years when a wait and see policy was followed. Importantly, immediate postoperative radiotherapy did not result in an additional need for conventional hormonal substitution treatment, or in an excess of epilepsy, cerebrovascular disease, and intracerebral malignancy in comparison to an expectant strategy. Furthermore, it is noteworthy that life expectancy was similar in both groups, and did not differ from the general Dutch population. Our survey thus suggests that immediate postoperative radiotherapy in case of residual NFA can be applied safely.

Local control rate after immediate postoperative radiotherapy reported here agrees with other studies, showing that 82% to 97% of patients remained free of tumor regrowth after 10 years of follow-up. Comparable with our data, a local control rate of only 40% to 70% at 5 years and of 15% to 50% at 10 years was documented previously when a wait and see policy was followed. I

Pituitary adenomas: long-term results for radiotherapy alone and post-operative radiotherapy.

Hughes MN, Llamas KJ, Yelland ME, Tripcony LB       Int J Radiat Oncol Biol Phys 1993 Dec 1;27(5):1035-43

Queensland Radium Institute, Royal Brisbane Hospital, Brisbane, Australia.

The study involved a retrospective review of outcome in a series of 268 patients with pituitary adenomas, treated at the Queensland Radium Institute from January 1962 to December 1986. The study population included 108 patients treated with radiotherapy alone and 160 patients treated by surgery and post-operative radiotherapy. For radiotherapy alone, the 10-year progression-free survival rate was 60%, and overall tumor control was obtained in 77%. Univariate analysis suggested that tumor type and radiotherapy field size were of prognostic significance. Multivariate analysis confirmed that Prolactinoma subtype and increasing radiotherapy field size were independently predictive of reduced progression-free survival. Long-term visual complications occurred in 1% of patients treated by radiotherapy alone. In patients treated by surgery and post-operative radiotherapy, the 10-year progression-free survival rate was 77%, and overall tumor control was achieved in 83%. Univariate analysis suggested that tumor type, completeness of surgical excision, and radiotherapy dose were predictive of outcome. However, on multivariate analysis, only the extent of surgical excision predicted prognosis independently. Long-term visual sequelae were noted in 3% of patients treated by surgery and post-operative radiotherapy. CONCLUSION: Both radiotherapy alone and post-operative radiotherapy are effective in long-term control of pituitary adenomas, and produce acceptably low complication rates.

Postoperative radiation therapy for pituitary adenoma.

Isobe K, Ohta M, Yasuda' S, Uno T, Hara R, Machida N, Saeki N, Yamaura A, Shigematsu N, Ito H    J Neurooncol 2000 Jun;48(2):135-40

Department of Radiology, Chiba University, School of Medicine, Japan.

A total dose of 48-60 Gy (median: 50 Gy) was delivered with a conventional fractionation schedule after surgery. Of 75 patients, 55 (73%) were followed for more than 5 years and 27 (36%) were followed for more than 10 years with a median of 95 months. RESULTS: Five- and 10-year local control probabilities were 87.1% and 85.0%, respectively. Univariate analysis revealed that age (p = 0.007), tumor volume smaller than 30 cm3 (p = 0.018) and the absence of prolactin secretion (p = 0.003) were significantly favorable prognostic factors for local control probability. After multivariate analysis combining these 3 factors, tumor volume smaller than 30 cm3 (p = 0.017) and age (p = 0.039) were statistically significant. Patients with prolactinoma greater than 30 cm3 showed particularly poor local control rates. No significant improvement of the local control rate was detected with increasing total irradiation doses between 48 and 60 Gy (p = 0.29). The most common side effect was hypopituitarism, and there were no severe sequelae such as optic neuropathy or brain necrosis. CONCLUSION: Except with prolactinoma, the dose of postoperative RT for pituitary adenoma should not exceed 50 Gy. Large prolactinoma, however, was very difficult to control with the irradiation doses between 50 and 60 Gy, and would be good candidates for stereotactic radiosurgery or stereotactic radiation therapy.