Comparative therapeutic efficacy of 177Lu-EDTMP and 153Sm-EDTMP in bone pain palliation in cancer patients with multiple skeletal metastases

Objectives To compare the therapeutic efficacy of [153]Sm-EDTMP and [177]Lu-EDTMP in painful wide spread skeletal metastases in breast, prostate and lung cancer patients

Methods Thirty patients (25 M: 5 F, mean age: 66.03 ± 14.69 years having advanced metastatic breast, prostate and lung cancer disease were recruited in the study. All these patients had clinical and radiological evidence of wide spread skeletal metastases and had severe bony pain despite receiving various analgesics. All the patients underwent baseline laboratory investigations (haematological and kidney functions). Only the patients having scintigraphic (99mTc-MDP) evidence of multiple skeletal metastatic sites were considered randomly for radionuclide therapy by using either [153]Sm-EDTMP or [177]Lu-EDTMP. The first group (n=20) was considered for radionuclide therapy with [153]Sm-EDTMP (58.25 ± 11.34 mCi; range: 36.4 to 77.23 mCi) and the second group (n=10) with [177]Lu-EDTMP (52.30 ± 15.12 mCi; range: 29 to 71 mCi) respectively. Following intravenous administration of each of the radionuclide, the patients underwent serial (3 h, 6 h, 24 h, 48 h, 96 h and 5 days post injection) whole body anterior and posterior imaging using a dual headed gamma camera. This imaging data were used for the absorbed dose calculations to the ‘metastatic lesions’ and the critical organs’ by MIRD schema using OLINDA (version 1.0). A correlation was seen, if any, between the absorbed dose to the bony metastatic lesions and pain relief assessment based upon the standard pain relief criteria. The patients were labelled as having complete response (pain score less 3.0), partial response (pain score between 4-8) and no-response (pain score more than 8.0) respectively.

Results A complete response was observed in 16/20 and 8/10 (80% each) in [153]Sm-EDTMP and [177]Lu-EDTMP treated groups respectively. A significant decline in pain score from the baseline (pre-treatment score) was observed in both the treatment groups at assessment period of 1,3, 6 & 8 weeks (P< 0.0001, 95% confidence interval). However, the decline became more prominent at 8 weeks of treatment in responders in each group. The observed decline in pain scoring at 8-weeks was 1.31±0.5 from 7.20±1.7 (baseline) and 1.63±0.52 from 7.9±1.5 (baseline) in [153]Sm-EDTMP and [177]Lu-EDTMP treated groups respectively. On the other hand, in non-responders (4/20 in [153]Sm-EDTMP group and 2/10 in [177]Lu-EDTMP group), the corresponding values of pain score reduction were 3.0 ± 2.0 (baseline 8.25± 1.50) and 4.0±0 (baseline 6.0) respectively. A mean absorbed dose to the metastatic lesions with each of the two radiopharmaceuticals used was 6.5±4.1 mSv/MBq. A positive correlation was observed between the absorbed dose to the metastatic lesions and the degree of the pain relief.

Conclusions [153]Sm-EDTMP as well as [177]Lu-EDTMP exhibited similar biodistribution pattern on serial scintigraphic data. The response rate for each radionuclide in terms of a significant reduction in pain score was evaluated as about 80.0%. A positive correlation was observed between the absorbed dose to the lesions and the observed pain relief assessment. Both the radionuclides thus offer an effective treatment at an affordable cost for bone pain palliation in cancer patients with painful wide spread skeletal metastases. And also offer good image quality for response assessment correlation with the individualized/personalized patients’ dosimetry.