Recurrent Pituitary Adenoma: Analysis of Risk Factors and Surgical Morbidity

Introduction: Recurrent disease is seen in 15% cases of pituitary adenoma following trans-sphenoidal resection. However, very little is known regarding risk factors for recurrence. Additionally, there is ambiguity on whether reoperations for recurrent disease are associated with higher morbidity as compared with primary surgery.

This study was done to identify clinical risk factors for recurrence and to assess surgical morbidity following reoperations for pituitary adenoma.

Materials and Methods: Retrospective chart review of all cases of pituitary adenoma treated between 2013 and 2017 at a single tertiary referral center was performed. Among 429 patients evaluated, 301 primary cases were included in the study.

“Clinically relevant recurrence” was defined as those cases with radiologically diagnosed recurrent disease that required intervention (reoperation or radiotherapy). To assess surgical morbidity, two parameters were considered—duration of hospital stay and CSF leak rates.

Results: Approximately one-fifth patients (18%, N = 53) of the total cases had radiologically diagnosed recurrent disease, out of which 6.6% (N = 20) were clinically relevant. Patients with recurrent disease were noted to be younger than patients who did not (mean, 49.6 years versus 54.5 months, p = 0.03). Gender distribution was noted to be similar (p = 0.69). Duration of follow-up was comparable between both the groups (p = 0.1964).

The cumulative rate of recurrence per year of follow-up showed that 80% of clinically relevant recurrent disease presented within first 24 months of follow-up following primary surgery. Mean duration between primary surgery and second intervention (re-operation or stereotactic radiotherapy) was 17.4 months (SD, 19.6 months).

On analyzing the clinical risk factors for recurrence, it was observed that extent of tumor resection (partial vs. total) was significantly different between the two groups (Partial resection rate: 39.6 versus 6.9%, p < 0.0001). Furthermore, it was noted that cavernous sinus involvement was also a significant predictor of recurrence (66 vs. 25%, p < 0.0001) and so was invasiveness of tumor (68 vs. 25%, p < 0.0001). On measuring the tumor volume, it was seen that larger tumors had a higher risk of developing recurrence (mean: 11.3 vs. 5 cm³, p < 0.0001). Type of tumor (functioning vs. nonfunctioning) was comparable between the two groups.

On comparing the surgical morbidity due to re-operation (for recurrent disease) with that due to primary surgery, it was found that re-operation was not associated with higher risk of CSF leak (primary surgery 29.56% vs. reoperation 21.42%). Additionally, patients admitted for reoperations showed similar length of hospital stay as primary surgery (median, 2 vs. 2 days).

Conclusion: Clinical risk factors for recurrent pituitary adenoma include large size, cavernous sinus involvement, tumor invasiveness and partial tumor resection during primary surgery. Re-operation for recurrent disease is not associated with increased surgical morbidity as compared with initial surgery.