In response to the original report by Li et al1 and the editorial published in Cancer, we would like to suggest a few points of discussion to promote a better understanding of the efficacy of high-intensity focused ultrasound (HIFU) ablation in the clinical therapy of malignant bone tumors. Thirteen of the patients had primary malignant bone tumors. Twelve of the primary tumors were osteosarcomas. The osteosarcomas were located in limbs (n = 7), iliums (n = 2), scapula (n = 1), pubis (n = 1), and ribs (n = 1). The patients were selected based on the following criteria: those with osteosarcoma histopathologically diagnosed by core biopsy; those at stage IIA and IIB without involvement of nerves or vessels; those nonresponsive to multiple courses of chemotherapy but rejecting amputation; those with strong willingness for limb salvage. Surgical operation of the osteosarcomas may cause serious wounds, complications, and disabilities when the tumors are located in the ilium, scapula, pubis, and limbs. These patients are not willing to undergo the surgical operation.
The therapeutic effect of high-intensity focused ultrasound ablation combined with chemotherapy in the salvage of limbs in 7 osteosarcoma patients has already been published in Cancer Biology and Therapy.2 All of the patients were alive 3 years after HIFU treatment. Five patients were alive at follow-up visits after 5 years. The 5-year survival rate was 71.4% in seven patients. Efficacy evaluation of HIFU treatment is attributed to the result of clinical synthetic judgment, including clinical manifestation, pain evaluation, biochemical examination, radiographic imaging examination, and tumor evaluation. Magnetic resonance imaging or positron emission tomography-computed tomography exams were performed 4 to 6 weeks before and after treatment to evaluate tumor necrosis and lesion size. HIFU treatment is different with the surgical operation. Noninvasive HIFU treatments may be done many times. The gold standard of HIFU treatment effect is freedom from local failure or progression. The World Health Organization standard was adopted to evaluate the effectiveness of HIFU treatment.
Therefore, we think that HIFU ablation is a safe and feasible method of treatment of bone tumors,3 but large-scale randomized clinical trials are necessary for confirmation.