Present and future technology for simultaneous superficial thermoradiotherapy of breast cancer

Abstract

This paper reviews systems and techniques to deliver simultaneous thermoradiotherapy of breast cancer. It first covers the clinical implementation of simultaneous delivery of superficial (microwave or ultrasound) hyperthermia and external photon beam radiotherapy, first using a Co-60 teletherapy unit and later medical linear accelerators. The parallel development and related studies of the SURLAS, an advanced system specifically designed and developed for simultaneous thermoradiotherapy, follows. The performance characteristics of the SURLAS are reviewed and power limitation problems at high acoustic frequencies (> 3MHz) are discussed along with potential solutions. Next, the feasibility of simultaneous SURLAS hyperthermia and IMRT/IGRT is established based on published and newly presented studies. Finally, based on the encouraging clinical results thus far, it is concluded that new trials employing the latest technologies are warranted along with further developments in treatment planning. Keywordsbreast; cancer; chest wall; heat; hyperthermia; radiation therapy; radiotherapy; radiosensitization; recurrence; thermoradiotherapy; simultaneous; ultrasound; intensity modulated Hyperthermia and CancerConventional hyperthermia in cancer therapy can be defined as the elevation of tissue temperatures to 41~43°C for more than 30 minutes. Hyperthermia is typically used as an adjunct therapy to radiotherapy and/or chemotherapy [1][2][3][4][5]. Many well-conducted clinical trials, including phase III multi-institutional trials following quality assurance guidelines, have shown that hyperthermia can significantly increase both local tumor control rates and duration of local control in tumors that recur or persist after surgery, radiotherapy and/or chemotherapy [6][7][8][9]. Furthermore, hyperthermia has been shown beneficial in the treatment of residual microscopic disease in the management of local-regional breast cancer [10], in the treatment of soft tissue sarcomas preoperatively with radiation [11], and in the treatment of deep pelvic tumors [12,13]. A significant survival benefit was also reported when hyperthermia was combined with brachytherapy in the treatment of glioblastoma multiforme [14] and with external beam radiotherapy in the treatment of recurrent head and neck cancer [15]. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptIn fact, when clinical trials have been conducted under widely accepted quality assurance guidelines-which implies matching the heating technology to the target site along with the implementation of a reasonable thermometry strategy-radiotherapy plus hyperthermia has always resulted in statistically better outcomes than radiotherapy alone [16]. Thermoradiotherapy of Breast CancerPatients with persistent and/or recurrent breast cancer and chest wall tumors have significantly benefited when hyperthermia has been added to their radiotherapy and/or chemotherapy regimens [17][18][19][20][21][22][23][24][25][26]. One of the physical reasons for the success of hyp...

Hypofractionated re-irradiation of large-sized recurrent breast cancer with thermography-controlled, contact-free water-filtered infra-red-A hyperthermia: a retrospective study of 73 patients

“…[27,28]). Preclinical and clinical studies showed a much better effect of combined RT/HT with simultaneous application [8,9,29], achieving a thermal enhancement ratio (TER) from . Mean temperature profiles within tissues during wIRA-exposure under steady state conditions.…”

Thermoradiotherapy planning: Integration in routine clinical practice

“…Because the effect of HT is no longer tumour selective when given simultaneously with RT, an increase in therapeutic ratio can only be obtained when the volume where RT and HT are given simultaneously can be geometrically restricted to the macroscopic tumour itself. Superficial and intracavitary HT equipment suitable for simultaneous RT + HT has become available [69][70][71][72] and is clinically applied [73], but such a good delineation is challenging for HT at deep-seated tumour locations as heating in normal tissue in the vicinity of the heated tumour region cannot be avoided due to heat conduction and blood flow, even when well-controlled high resolution HT techniques are used. The tumour delineation must therefore come primarily from RT and image-guided radiotherapy techniques which permit a very precise dose control and TRTP could be used to devise an optimal combination of RT and HT treatment plans achieving high TER in tumour tissue while keeping TER in normal tissue low, even when RT and HT are given simultaneously.…”

Tumor radiation response enhancement by acoustical stimulation of the vasculature

“…Hyperthermia has been used to enhance successfully the effects of radiation (2) and is currently being pursued for liposomalmediated drug delivery (10), simultaneous thermal treatment with radiation (11), and MRI guidance for higher-powered thermal ablation (12). It has demonstrated excellent clinical results (13).…”