Purpose:
To examine the clinical validity of the concept of acquiredchemoresistance in recurrent Group B retinoblastoma lesions.
Methods:
Retrospective Case Series.
Results:
: Over a two-year period from 2005 to present, we identifiedfive patients with recurrent Group B retinoblastoma lesionsappearing several months following completion of chemoreductionand laser consolidation. Rather than assume that regrowth wasa result of acquired resistance to the standard CEV regimen,we assumed inadequate laser consolidation. The original chemotherapeuticagents were restarted. In each case, reduction of tumor volumeresulted. Photograph (A) demonstrates a lesion inferior to thefovea that recurred following completion of 9 cycles of CEVand laser consolidation. A presumed retinocytoma is presentsuperior to the disc. Photograph (B) shows the clinical responsein the recurrent lesion after one additional cycle of CEV systemicchemotherapy.
Conclusions:
Patients with recurrent Group B retinoblastoma lesions followingchemoreduction and laser consolidation have acquired resistanceto the original drugs. While there are well-documented mechanismsfor such multi-drug resistance (p-glycoprotein), our reviewsuggests that this resistance mechanism may not be clinicallyrelevant in this subgroup of retinoblastoma patients. Becausethese patients continued to respond to CEV at the original doses,it is likely that recurrent growth in these cases is due toinadequate local consolidation.
Keywords: retinoblastoma • oncology • laser