Minimally invasive therapy has been investigated as a potential means of treating breast tumors with minimal disruption to adjacent soft tissues. The purpose of this approach is to facilitate improved cosmesis and to offer treatment to women who are unfit for surgery (Hall-Craggs and Vaidya, 2002).
Interstitial laser therapy (ILT) is a microinvasive technique that uses image-guided needle probes to deliver laser energy into a tumor to slowly heat and destroy the tumor cells. It has been proposed as a minimally invasive alternative to lumpectomy for fibroadenomas (benign tumors) that are 2 cm or less in size and it is also under investigation for treatment of localized breast cancers. Potential advantages of laser ablation compared to surgical excision include: shorter procedure time, outpatient setting, smaller incision and minimal scarring, less bleeding and tissue damage, lowered risk of infection due to heat sterilization of surrounding tissue and decreased healing time.
The Novilase Interstitial Laser Therapy (Novian Health, Inc., Chicago, IL) system received 510(k) marketing clearance from the U.S. Food and Drug Administration in 2007 for the treatment of breast fibroadenomas that are 2 cm or less in size. It is also used for general surgery procedures (e.g., incision, excision and ablation of soft tissues; coagulative necrosis and interstitial laser coagulation of soft tissue).
In an uncontrolled prospective study, Basu et al (1999) reported the results of the effect of interstitial laser hyperthermia in breast fibroadenomas as an out-patient procedure. Patients younger than 35 years (n = 27) received laser phototherapy of their breast fibroadenomas under real-time ultrasound monitoring. Nd:YAG laser was used in a continuous wave mode to produce interstitial hyperthermia. Follow-ups were done at 2, 4, and 8 weeks. There was a significant decrease in clinical and sonographic sizes (p < 0.001). Follow-up ultrasound showed a progressive change of hyperechoic texture, from a heterogeneous to a nearly homogeneous one. There were minimal scars (2 to 3 mm) and no keloid or abscess formation. The authors concluded that interstitial laser hyperthermia is a safe, precise, and minimally invasive outpatient procedure for in situ destruction of breast fibroadenomas, although it should be noted that excisional biopsy of residual lumps was performed.
In a non-randomized controlled trial, Dowlastshahi et al (2000) reported the results of stereotactically guided laser ablation of mammographically detected breast tumors (n = 36). Patients were treated on a stereotactic table, using a 16- to 18-gauge laser probe, with an optic fiber transmitting a pre-determined amount of laser energy. A multi-sensor thermal probe was inserted into the breast adjacent to the laser probe to monitor treatment. In the last 10 patients, the tumor blood flow was evaluated before and after laser therapy with contrast-enhanced color Doppler ultrasound. One to 8 weeks after laser therapy, the tumors were surgically removed and serially sectioned. Complete necrosis occurred in 66 % of the tumors. Microscopic examination at 1 week showed disintegration of malignant cells, with peripheral acute inflammatory response and at 4 to 8 weeks extensive fibrosis. Contrast-enhanced color Doppler ultrasound revealed loss of tumor circulation after therapy, and positron emission tomography scan correlated well with histologic findings. There were no systemic adverse effects. Two patients sustained 3 x 4-mm skin burns around the laser needle. The authors concluded that a stereotactically guided minimally invasive technique may be effective for the treatment of mammographically detected breast cancer.
Haraldsdóttir et al (2008) reported the results of ILT on invasive breast cancer patients (n = 24). All study patients underwent mammography, ultrasound and core biopsy before treatment. The tumors were classifed as invasive ductal carcinoma (n = 15), lobular carcinoma (n = 8) and lobular-ductal cancer (n = 1). Average tumor diameter was 14 mm on ultrasound (range of 5 to 35). Patients were treated in the out-patient clinics under local anesthesia. Probes were placed under ultrasound guidance in 19 patients, and ILT was performed with a diode laser. Standard surgical excision was performed 12 (range of 4 to 23) days after ILT and was preceded by Doppler ultrasound. Treatment-induced necrosis of invasive cancer was 33 % (range 0 to 100) and was complete in 3 patients. At follow-up before surgery, the extent of laser damage could not be judged with ultrasound, although abolished tumor blood flow was demonstrated after treatment resulting in large necroses. Efficacy of treatment varied negatively with tumor size. The inefficacy of ILT was mainly due to the under-estimation of tumor size by mammography and ultrasound and the shortcomings of these methods to demonstrate tumor borders, tumor irregularity and carcinoma in situ (CIS). Interstitial laser therapy was well tolerated. Five patients had breast tenderness and 3 patients had pain during the first day after treatment. Small skin necroses were observed in 2 patients. The authors concluded that small breast cancers can be treated radically with ILT and that the method may become useful in the treatment of breast cancer but needs further refinement, even for small well-defined breast cancers, if it is going to be employed for radical treatment
No professional medical society recommends the use of ILT for breast tumors. Excisional biopsy is considered the gold standard for evaluating breast masses and it is both diagnostic and therapeutic. A completely removed mass with good margins of normal tissue may mean that further surgery is not required (Klein, 2005).
Recommendations by the Canadian Association of Radiation Oncologists (1998) on the palpable breast lump stated that whenever reasonable doubt remains as to whether a lump is benign or malignant, a biopsy to remove the entire lump in one piece along with a surrounding cuff of normal tissue for cytological examination should be carried out.
An assessment of ILT for fibroadenomas by the National Institute for Clinical Excellence (NICE, 2005) concluded that "current evidence on the safety and efficacy of interstitial laser therapy for fibroadeomas of the breast does not appear adequate for this procedure to be used without special arrangements for consent and for audit or research." The assessment noted that adverse events include local burns at the needle site and theoretical complications include local infection, and bleeding if the needle strikes a blood vessel. Furthermore, the specialist advisors noted that the lack of material for biopsy means that the benign diagnosis cannot be confirmed.
An assessment of ILT for breast cancer by the National Institute for Clinical Excellence (NICE, 2004) concluded that "Current evidence on the safety and efficacy of interstitial laser therapy for breast cancer does not appear adequate to support the routine use of this procedure. It is suitable for use only within good-quality research studies approved by a research ethics committee and with explicit patient consent." The assessment stated that publication of safety and efficacy outcomes will be useful in reducing the current uncertainty. The assessment stated that the evidence of efficacy was limited to three small case series and one case report. The Specialist Advisors to NICE noted that it was still uncertain whether the procedure could achieve thermal ablation of all malignant tissue. They also noted that there were no data comparing outcomes of the procedure with those of wide excision and radiotherapy. A Specialist Advisor stated that the potential adverse effects of the procedure includes necrosis, hemorrhage, and liquefaction caused by overheating of tissue.
Novian Health, Inc. is currently conducting a prospective, observational multi-center study which will evaluate the clinical outcomes of Novilase for benign breast fibroadenomas versus lumpectomy. A trial on the use of Novilase for malignant breast tumors is also being planned by Novian Health, Inc.
At this time, it is not clear who might benefit from ILT for fibroadenomas (e.g., age subgroup, tumor size, etc.) or malignant breast tumors. Benign breast lumps may spontaneously resolve on their own and require no intervention. However, some researchers consider fibroadenomas a long-term risk factor for breast cancer (Dupont, et al, 1994; El-Wakeel and Umpleby, 2003). While a few researchers have reported early results with lLT of breast tumors, no controlled or comparative trials to evaluate ILT versus lumpectomy have been published. Thus, it is not known whether ILT is as effective as lumpectomy for breast tumors.
In a prospective non-randomized study, Wietzke-Braun et al (2004) examined the quality-of-life (QOL) and outcome of ultrasound-guided laser interstitial thermo-therapy (US-LITT) in patients with liver metastases of colorectal cancer. A total of 45 patients with liver metastases of colorectal cancer were palliatively treated by US-LITT. Patient survival was analyzed by the Kaplan-Meier method and the QOL questionnaire C30 of the European Organization for Research and Treatment of Cancer before, and 1 week, 1 month, and 6 months after initiation of US-LITT. Median survival after initiation of US-LITT was 8.5 +/- 0.7 months with a range of 1.5 to 18 months. Body weight was constant 1 month after US-LITT. In the multi-variate analyses, QOL symptoms and functioning scales did not deteriorate in patients alive at 6 months after initiation of US-LITT. Uni-variate analyses outlined a significant increase of the pain subscale before and at 1 week after US-LITT. The authors concluded that this study first described the QOL in patients with liver metastases of colorectal cancer treated by US-LITT. Potential benefits of the minimal invasive procedure could be prolonged survival time by preserved QOL, but this first impression needs to be verified in a comparative study.
The Swedish Council on Health Technology Assessment's report on LITT for liver metastases (SBU, 2011) states that this method is experimental. It is unclear if LITT extends life in patients with liver metastases; comparative studies are lacking. Studies published to date show that LITT can ablate metastases, and that risks associated with the procedure are minor. However, the beneficial effects of metastases ablation, in terms of symptoms and QOL, has not been demonstrated in the literature. The SBU assessment notes that use of LITT should be limited to controlled trials.
Vogl et al (2007) evaluated the feasibility, safety and effectiveness of CT-guided and MR-thermometry-controlled LITT in adrenal metastases. A total of 9 patients (7 males, 2 females; average age of 65.0 years; range of 58.7 to 75.0 years) with 9 unilateral adrenal metastases (mean diameter 4.3 cm) from primaries comprising colorectal carcinoma (n = 5), renal cell carcinoma (n = 1), esophageal carcinoma (n = 1), carcinoid (n = 1), and hepato-cellular carcinoma (n = 1) underwent CT-guided, MR-thermometry-controlled LITT using a 0.5 T MR unit. Laser interstitial thermo-therapy was performed with an internally irrigated power laser application system with an Nd:YAG laser. A thermo-sensitive, fast low-angle shot 2D sequence was used for real-time monitoring. Follow-up studies were performed at 24 hrs and 3 months and, thereafter, at 6-month intervals (median of 14 months). All patients tolerated the procedure well under local anesthesia. No complications occurred. Average number of laser applicators per tumor: 1.9 (range of 1 to 4); mean applied laser energy 33 kJ (range of 15.3 to 94.6 kJ), mean diameter of the laser-induced coagulation necrosis 4.5 cm (range of 2.5 to 7.5 cm). Complete ablation was achieved in 7 lesions, verified by MR imaging; progression was detected in 2 lesions in the follow-up. The authors concluded that these preliminary results suggested that CT-guided, MR-thermometry-controlled LITT is a safe, minimally invasive and promising procedure for treating adrenal metastases.
Schwarzmaier et al (2006) examined the survival after LITT in 16 patients suffering from recurrent glioblastoma multiforme. All patients received standard chemotherapy (temozolomide). The median OS time after the first relapse was 9.4 months, corresponding to a median OS time after laser irradiation of 6.9 months. During the study, however, the median survival after laser coagulation increased to 11.2 months. This survival time is substantially longer than those reported for the natural history (less than 5 months) or after chemotherapy (temozolomide: 5.4 to 7.1 months). These researchers concluded that cytoreduction by laser irradiation might be a promising option for patients suffering from recurrent glioblastoma multiforme. In addition, the data indicate the presence of a substantial learning curve. They stated that future work should optimize the therapeutic regimen and evaluate this treatment approach in controlled clinical trials.
Hawasli et al (2012) described the novel use of AutoLITT System (Monteris Medical, Winnipeg, MB) for focused LITT using intra-operative MRI and stereotactic image guidance for the treatment of metastatic adenocarcinoma to the left insula. The patient is a 61-year old right-handed male with a history of metastatic adenocarcinoma of the colon. He has previously undergone resection of multiple lesions, Gamma Knife and whole brain radiation. Despite treatment to a left insular tumor, serial imaging revealed that the lesion continued to enlarge. Given the refractory nature of this tumor to radiation and the deep seated location, the patient elected to undergo LITT treatment. The center of the lesion and entry point on the scalp were identified using STEALTH (Medtronic, Memphis, TN) image-guided navigation. The AXiiiS Stereotactic Miniframe (Monteris Medical, Winnipeg, MB) for the LITT system was secured onto the skull and a trajectory was defined to achieve access to the centroid of the tumor. After performing a burr hole, a gadolinium template probe was inserted into the AXiiiS base. The trajectory was confirmed via an intra-operative MRI and the LITT probe driver was attached to the base and CO2-cooled, side-firing laser LITT probe. The laser was activated and thermometry images were obtained. Two trajectories, posterior-medial and antero-lateral, produced satisfactory tumor ablation. The authors concluded that LITT using intra-operative MRI and stereotactic image guidance is a newly-available, minimally-invasive, and therapeutically viable technique for the treatment of deep seated brain tumors.
Saccomandi et al (2011) developed and verified a theoretical model to reproduce the thermal response of pancreatic tissue undergoing laser-interstitial thermal therapy (LITT). The model provided the evaluation of: (i) ablated volumes induced by thermal ablation; (ii) tissue response time to irradiation; and (iii) heat extinction time. Theoretical volume values were compared with ex-vivo healthy tissue and in-vivo healthy and neoplastic tissue volume values. The theoretical model takes into account the differences between healthy and neoplastic tissue due to blood perfusion. Mathematical model showed that ablated volume of ex-vivo healthy tissue is greater than in-vivo one after the same treatment. Moreover, ablated neoplastic in-vivo tissue volume is greater than healthy in-vivo one, because of tumor angiogenesis. Ablated volume values were compared with experimental data obtained by laser treatment of 30 ex-vivo porcine pancreases. Experimental ablated volume values show a good agreement with theoretical values, with an estimated increase of 61 % when power increases from 3 W to 6 W, versus 46 % of experimental data, and an estimated increase of 14 % from 6 W to 10 W, versus 21 % of experimental values. LITT could be an alternative or a neo-adjuvant treatment to surgical resection for pancreas cancer removal, and the proposed model could be the basis to supervising the evolution of ablated volumes during tumor treatment.
Dossing and colleagues (2011) evaluated the long-term effectiveness of interstitial laser photocoagulation (ILP) in solitary benign thyroid nodules. A total of 78 euthyroid outpatients (45 participating in randomized trials) with a benign solitary solid and scintigraphically cold thyroid nodule causing local discomfort were assigned to ILP. Interstitial laser photocoagulation (using 1 laser fiber) was performed under continuous ultrasound (US) guidance and with an output power of 1.5 to 3.5 W. Thyroid nodule volume was assessed by US and thyroid function determined by routine assays, before and during follow-up. Pressure symptoms and cosmetic complaints were evaluated on a visual analog scale (0 to 10 cm). Of the 78 patients, 6 had thyroid surgery 6 months after ILP and 3 were lost to follow-up. The median follow-up for the remaining 69 patients was 67 months (range of 12 to 114). The overall median nodule volume decreased from 8.2 ml (range of 2.0 to 25.9) to 4.1 ml (range of 0.6 to 33.0; p < 0.001) at the final evaluation, corresponding to a median reduction of 51 % (range of -194 % to 95 %). This correlated with a significant decrease in pressure as well as cosmetic complaints. After 12 to 96 months (median of 38 months) of ILP, 21 patients (29 %) had thyroid surgery because of an unsatisfactory result. All had benign histology. Thyroid function was unaltered throughout and side effects were restricted to mild local pain. The authors concluded that US-guided ILP results in a satisfactory long-term clinical response in the majority of patients with a benign solitary solid cold thyroid nodule. Moreover, they stated that further large-scale studies should aim at optimizing selection criteria for ILP, preferably in randomized studies.
Rahmathulla and colleagues (2012) noted that whole-brain radiotherapy and stereotactic radiosurgery (SRS) play a central role in the treatment of metastatic brain tumors. Radiation necrosis occurs in 5 % of patients and can be very difficult to treat. The available treatment options for radiation necrosis include prolonged high-dose corticosteroids, hyperbaric oxygen, anti-coagulation, bevacizumab, and surgical resection. These investigators presented the first report and results using LITT for medically refractory radionecrosis in a 74-year old diabetic patient who had a history of non-small cell lung cancer with brain metastases and subsequent treatment with SRS, and who presented with a focal lesion in the left centrum semiovale with progressively worsening edema. Image findings were consistent with radiation necrosis that was refractory despite prolonged, high-dose steroid therapy. His associated co-morbidities obviated alternative interventions and the lesion was not in a location amenable to surgical resection. These investigators used LITT to treat the biopsy-proven radionecrosis. The procedure was well-tolerated and the patient was discharged 48 hours post-operatively. Imaging at 7-week follow-up showed near complete resolution of the edema and associated mass effect. Additionally, the patient was completely weaned off steroids. To the authors' knowledge, this is the first report using LITT for the treatment of focal radiation necrosis. The authors concluded that LITT may be an effective approach for patients with medically refractory radiation necrosis with lesions not amenable to surgical decompression.
In summary, ILT may be a promising minimally invasive technique for breast tumors and other tumors/malignancies, however, there is insufficient evidence of its clinical effectiveness.