Background: Surgery is the primary mode of therapy for non-functioning pituitary adenomas(NFPA). The post-operative management of NFPA is a challenge because of a lack of knowledge regarding factors influencing remnant tumour growth that is clinically significant.
Aims: To identify radiological factors that predict the need for secondary intervention after surgical resection of NFPAs.
Methods: This is a single-centre retrospective study of surgically resected NFPAs in patients with pre- and serial postoperative MR imaging followed for at least a year. Tumour characterisation were performed by a single operator from pre-operative(tumour volume and extrasellar extension) and serial post-operative images(remnant volume, remnant site and growth rate). Secondary intervention was the outcome measure. The CVs for pre- and post-operative tumour volume from 8 subjects measured twice were 4% and 7% respectively.
Results: 85 patients(49 men, mean age at surgery: 53±16 years) with a median follow up of 5.1 years (range:1.2-20.0) were studied. The pre-operative median volume was 3447mm3(526-99850). Post-operatively, 67% had remnant tumours, 60% of which were extrasellar with a median remnant volume of 319mm3(33-5475) and remnant growth rate of 51.8mm3/year(0-1963.2). 25% of patients required secondary intervention(second surgery: 8 and irradiation: 13). Kaplan-Meier analysis showed that the rate of secondary intervention when required was 65% at 5 years and 100% by 10 years. Cox regression analysis identified presence of post-operative remnant(HR: 5.1, CI: 1.6-11.2, p=0.01), remnant growth rate(HR: 3.3, CI: 2.1-7.0, p<0.01) and pre-operative suprasellar invasion(HR: 1.2, CI: 1.1-1.9, p=0.02) as independent predictors of secondary intervention.
Summary: In surgically treated NFPAs, secondary intervention occurred in 25%, all within the first decade. This was determined by pre and post-operative tumour characteristics.
Conclusion: In surgically resected NFPAs(i)secondary intervention is unlikely to be required beyond 10 years (ii)the presence of tumour remnant is the primary prognostic indicator (iii)intensity of follow up should be tailored to imaging characteristics