Purpose
Histopathologic high risk factors(HRF) are well established prognostic markers in retinoblastoma(Rb).Metastasis Associated in Colon Cancer1(MACC1) gene is reported as an important prognostic indicator for systemic metastasis and metastasis-free survival in many cancers like Colon,Breast,and Gastric.This study aims to evaluate MACC1 expression in Rb cases,with and without HRF,and its possible association with clinical outcome.
Methods
After IRB approval,medical records of histopathologically proven Rb cases with(n=12) and without HRF(n=11) were retrieved from the Ocular Oncology Service and Ophthalmic Pathology Laboratory,LVPEI.Of these,19(83%) cases had undergone primary enucleation and 4(17%) secondary enucleation following poor response to systemic chemotherapy.Patients with HRF underwent bone marrow and cerebro-spinal fluid evaluation for metastasis and treated using the standard clinical protocol with 6 cycles of adjuvant systemic chemotherapy(Vincristine,Etoposide,Carboplatin).RNA was isolated from FFPE tissues(central calotte only) and evaluated for MACC1 expression by semi-quantitative PCR.The relative gene expression was quantified using Image Lab software(Bio-Rad).Expression levels were correlated with HRF and clinical outcome of patients.
Results
Mean age of patients at presentation was 30 months.Bilateral Rb was noted in 47%(11/23) cases with 65% being male.Leucokoria was the chief presenting clinical feature(78%).In HRF cases,the average MACC1 expression was increased(3.46 vs 2.68, p=0.09) with 50% showing more than 3 fold increase compared to negative controls.In no HRF cases,≥ 3 fold expression of MACC1 was seen in 18% of cases.MACC1 expression was marginally increased in poorly differentiated cases(48%) compared to well and moderately differentiated cases(3.15 vs 3.02fold,p=0.4).It was also higher in cases that underwent primary enucleation(83%), compared to those who underwent secondary enucleation post-systemic chemotherapy (4/23)(3.15 vs 2.8fold,p=0.67).At a mean follow-up of 27 months(3-48 months),except 1 patient who died at 3 months post enucleation,none of them showed evidence of local recurrence or metastasis.
Conclusions
This study shows that high MACC1 expression in Rb correlates with histologic risk factor,thus indicating its possible role in tumor invasion and metastasis.However,further studies on larger cohort and multivariate analysis is warranted to establish its role as a potential prognostic marker in retinoblastoma.
Keywords: 703 retinoblastoma •
638 pathology: human •
744 tumors