A retrospective study on adjuvant chemotherapy in retinoblastoma: validation of the new recommendation against treatment for pT2a tumors based on the 8th AJCC classification.

backgroundRetinoblastoma (RB) is an intraocular malignant tumor detected in early childhood with variable global impact. Histopathological classification of the tumor in enucleated globes with RB is the key for the decision of adjuvant chemotherapy use. We aim to validate the use of adjuvant chemotherapy in cases with combined pre-laminar/intralaminar optic nerve (ON) invasion and focal choroidal invasion according to the American Joint Committee on Cancer (AJCC) 8th classification.

methodsThis is a retrospective study conducted at King Abdulaziz University Hospital (KAUH) and King Khalid Eye Specialist Hospital (KKESH) in Riyadh, Saudi Arabia of all RB cases who underwent enucleation over 22 years (2000 to 2021). The histopathological findings were reviewed to identify the enucleated globes classified as pT2a tumors, as an inclusion criterion. Basic demographic and clinical data were collected via chart review Simple descriptive and basic statistical analysis of the data was used where applicable.

resultsThirty-one patients who had an enucleated globe with RB that fit into the above classification were included. Sixteen were males and 15 were females. The median age was 14 months (IQR = 14 months). Most of the patients (93.5%) had no family history of RB. The commonest presentation was leukocoria in 87.1% followed by squint in 32.3%. Fourteen patients (45.2%) were treated by enucleation alone while 17 patients (54.8%) received adjuvant chemotherapy. Out of these, 7 patients had unilateral RB and the remaining 10 patients had bilateral RB. None of our patients developed recurrence or metastatic disease irrespective of the indication for adjuvant chemotherapy use after a maximum period of follow up reaching 17.84 years and a median of 10.6 years (IQR = 5.92).

conclusionsIn patients with 8th AJCC histopathological classification of pT2a, chemotherapy following enucleation might not be justified. The outcome in our untreated group of patients did not differ from the treated group with the absence of metastasis after a relatively long period of follow up with a median exceeding 10 years in both groups. Therefore, the risk and benefit of post enucleation adjuvant chemotherapy in the treatment of unilateral RB should be carefully decided and discussed with the primary caregivers taking into consideration the most recent evidence and recommendations in the literature.