Phase I Trial of Carboplatin and Gemcitabine Chemotherapy and Stereotactic Ablative Radiosurgery for the Palliative Treatment of Persistent or Recurrent Gynecologic Cancer

Stereotactic Ablative Radiotherapy for Gynecological Oligometastatic and Oligoprogessive Tumors

Importance

The role of stereotactic ablative radiotherapy (SABR) for gynecologic malignant tumors has yet to be clearly defined despite recent clinical uptake.

Objective

To evaluate the outcomes of SABR in patients with oligometastatic and oligoprogressive gynecologic cancers.

Design, Setting, and Participants

In this retrospective pooled analysis, patients with oligometastatic and oligoprogressive gynecologic cancers receiving SABR at 5 institutions from Canada and the US were studied. Data were collected from January 2011 to December 2020, and data were analyzed from January to December 2023.

Exposure

Stereotactic ablative radiotherapy.

Main Outcomes and Measures

Cumulative incidence of local and distant recurrence, chemotherapy-free survival (CFS), and overall survival (OS) probabilities after SABR were calculated using Kaplan-Meier methods. Univariable and multivariable analysis was conducted using Cox regression methods.

Results

A total of 215 patients with 320 lesions meeting criteria were included in the analysis; the median (range) age at primary diagnosis was 59 (23-86) years. The median (range) follow-up from SABR was 18.5 (0.1-124.5) months. The primary site included the endometrium (n = 107), ovary (n = 64), cervix (n = 30), and vulva or vagina (n = 14). Local cumulative incidence of recurrence was 13.7% (95% CI, 9.4-18.9) and 18.5% (95% CI, 13.2-24.5) at 1 and 5 years, respectively. Distant cumulative incidence of recurrence was 48.5% (95% CI, 41.4-55.1) and 73.1% (95% CI, 66.0-79.0) at 1 and 5 years, respectively. OS was 75.7% (95% CI, 69.2-81.1) and 33.1% (95% CI, 25.3-41.1) at 1 and 5 years, respectively. The median CFS was 21.7 months (95% CI, 15.4-29.9). On multivariable analysis, local recurrence was significantly associated with nodal metastasis, lesion size, biologically effective dose, treatment indication, institution, and primary disease type. Distant progression-free survival was associated with nodal targets and lesion size. OS and CFS were significantly associated with lesion size.

Conclusions and Relevance

In this study, SABR appeared to have excellent local control with minimal toxic effects in this large patient group, and certain patients may achieve durable distant control and OS as well. It may be possible to delay time to chemotherapy in select patient subtypes and therefore reduce associated toxic effects. Prospective multicenter trials will be critical to establish which characteristics procure the greatest benefit from SABR use and to define the ideal time to implement SABR with other oncologic treatments.

Stereotactic Body Radiation Therapy for Gynecologic Malignancies: A Case-Based Radiosurgery Society Practice Review

PURPOSE

The use of stereotactic body radiation therapy (SBRT) for gynecologic malignancies is controversial. We discuss certain circumstances when highly precise SBRT may be a useful tool to consider in the management of selected patients.

METHODS AND MATERIALS

Case selection included the following scenarios, the first 2 with palliative intent, para-aortic nodal oligorecurrence of ovarian cancer, pelvic sidewall oligorecurrence of cervical cancer, and inoperable endometrial cancer boost after intensity modulated radiation to the pelvis treated with curative intent. Patient characteristics, fractionation, prescription dose, treatment technique, and dose constraints were discussed. Relevant literature to these cases was summarized to provide a framework for treatment of similar patients.

RESULTS

Treatment of gynecologic malignancies with SBRT requires many considerations, including treatment intent, optimal patient selection, fractionation selection, tumor localization, and plan optimization. Although other treatment paradigms including conventionally fractionated radiation therapy and brachytherapy remain the standard-of-care for definitive treatment of gynecologic malignancies, SBRT may have a role in palliative cases or those where high doses are not required due to the unacceptable toxicity that may occur with SBRT.

CONCLUSIONS

A case-based practice review was developed by the Radiosurgery Society to provide a practical guide to the common scenarios noted above affecting patients with gynecologic malignancies.

Role of stereotactic body radiotherapy in gynecologic radiation oncology

Stereotactic body radiotherapy (SBRT, also referred to as stereotactic ablative radiotherapy (SABR)) has been used in the treatment of primary and metastatic solid tumors, and increasingly so in gynecologic oncology. This review article aims to summarize the current literature describing the utility of SBRT in the primary, recurrent, and limited metastatic settings for gynecologic malignancies. The use of SBRT in both retrospective and prospective reports has been associated with adequate control of the treated site, particularly in the setting of oligometastatic disease. It is not, however, recommended as an alternative to brachytherapy for intact disease unless all efforts to use brachytherapy are exhausted. While phase I and II trials have established the relative safety and potential toxicities of SBRT, there remains a dearth of phase III randomized evidence, including the use of immunotherapy, in order to better establish the role of this technique as a method of improving more global outcomes for our patients with gynecologic cancers.

Long-term survival following definitive radiation therapy for recurrence or oligometastases in gynecological malignancies: A landmark analysis

OBJECTIVE

Radiation therapy (RT) may improve outcomes for patients with oligometastatic cancer. We sought to determine if there are long-term survivors treated with definitive RT for recurrent or oligometastatic gynecological cancer (ROMGC), and to evaluate the clinical and disease characteristics of these patients.

METHODS

We performed a landmark analysis in 48 patients with ROMGC who survived for ≥5 years following definitive RT of their metastasis. Patient characteristics were extracted from the medical record. DFS was modeled using the Kaplan-Meier method.

RESULTS

This cohort included 20 patients (42%) with ovarian cancer, 16 (33%) with endometrial cancer, 11 (23%) with cervical cancer, and one (2%) with vaginal cancer. The sites of ROMGC were the pelvic (46%), para-aortic (44%), supraclavicular (7%), mediastinal (4%), axillary (4%) lymph nodes and the lung (5.5%). Median total RT dose and fractionation were 62.1 Gy and 2.1 Gy/fraction; one patient was treated with SBRT. 32 patients (67%) received chemoradiation; these patients had higher rates of median DFS than those treated with RT alone (93 vs. 34 months, P = 0.05). At median follow-up of 11.7 years, 11 (23%) patients had progression of disease. 20 (42%) patients had died, 9 (19%) died from non-gynecologic cancer and 8 (17%) from gynecologic cancer (three were unknown). 25 (52%) patients were alive and disease-free (10 initially had endometrial cancer [63% of these patients], eight had cervical cancer [73%], six had ovarian cancer [30%], one had vaginal cancer [100%]).

CONCLUSIONS

Long-term survival is possible for patients treated with definitive RT for ROMG, however randomized data are needed to identify which patients derive the most benefit.

Addressing hepatic metastases in ovarian cancer: Recent advances in treatment algorithms and the need for a multidisciplinary approach

The lifetime risk for ovarian cancer incidence is 1.39% and the lifetime risk of death is 1.04%. Most ovarian cancer patients are diagnosed at advanced stages (III, IV) because there were no specific symptoms or existing screening tests. Liver metastases have been found in up to 50% of patients dying of advanced ovarian cancer. Recent studies indicate the need for a multidisciplinary approach from initial diagnosis to oncologic surgery and chemotherapy treatment, mandating the involvement of gynecologic oncologists, surgical oncologist, medical oncologists, hepatobiliary surgeons, and interventional radiologists.

Stereotactic body radiation therapy for oligometastatic gynecologic malignancies: A systematic review

OBJECTIVE

To assess the efficacy and safety of stereotactic body radiation therapy (SBRT) for oligometastatic gynecologic malignancies.

METHOD

A comprehensive search of the PubMed, Medline, and EMBASE databases was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. "Oligometastatic" was defined as a limited number of uncontrolled/untreated metastatic lesions (typically ≤ 5), including regional nodal metastases. Primary outcomes were response rate (complete response or partial response), local control of oligometastatic lesions, and toxicity.

RESULTS

Of 716 screened records, 17 studies (13 full length articles, 4 conference abstracts) were selected and analyzed as 16 unique studies. A total of 667 patients were treated with ~1071 metastatic lesions identified. Primary sites included ovarian (57.6%), cervical (27.1%), uterine (11.1%), vaginal (0.4%), vulvar (0.3%), and other/unspecified (3.4%). Most patients (65.4%) presented with a single metastatic lesion. Metastatic lesion sites included the abdomen (44.2%), pelvis (18.8%), thorax (15.5%), neck (4.6%), central nervous system (4.3%), bone (1.6%), and other/unspecified (11%). Of the lesions, 64% were nodal. Response rate (among 8 studies) ranged from 49% to 97%, with 7/8 studies reporting > 75% response rate. Local control ranged from 71% to 100%, with 14/16 studies reporting ≥ 80% local control. No grade ≥ 3 toxicities were observed in 9/16 (56%) studies. Median progression-free survival (PFS) (among 10 studies) ranged from 3.3 months to 21.7 months. Disease progression most commonly occurred outside of the SBRT radiation field (79% to 100% of failures).

CONCLUSIONS

SBRT for oligometastatic gynecologic malignancies is associated with favorable response and local control rates but a high rate of out-of-field progression and heterogeneous PFS. Additional study into rational combinations of SBRT and systemic therapy appears warranted to further improve patient outcomes.

Determinants of Sensitivity to Radiotherapy in Endometrial Cancer

Radiotherapy is one of the cornerstone treatments for endometrial cancer and has successfully diminished the risk of local recurrences after surgery. However, a considerable percentage of patients suffers tumor relapse due to radioresistance mechanisms. Knowledge about the molecular determinants that confer radioresistance or radiosensitivity in endometrial cancer is still partial, as opposed to other cancers. In this review, we have highlighted different central cellular signaling pathways and processes that are known to modulate response to radiotherapy in endometrial cancer such as PI3K/AKT, MAPK and NF-κB pathways, growth factor receptor signaling, DNA damage repair mechanisms and the immune system. Moreover, we have listed different clinical trials employing targeted therapies against some of the aforementioned signaling pathways and members with radiotherapy. Finally, we have identified the latest advances in radiotherapy that have started being utilized in endometrial cancer, which include modern radiotherapy and radiogenomics. New molecular and genetic studies in association with the analysis of radiation responses in endometrial cancer will assist clinicians in taking suitable decisions for each individual patient and pave the path for personalized radiotherapy.

[Radiotherapy for ovarian carcinoma management: Literature review]

Ovarian cancer is the fifth most common cancer in women in France with 4714 new cases in 2017. More than 70% of patients whose disease is initially locally advanced will present locoregional or distant recurrence. Therapeutic options in this situation are not consensual. They are based on chemotherapy possibly associated with an iterative cytoreductive surgery when it is bearable by the patient. The place of radiotherapy in the management of the disease is hidden in the vast majority of national or international standards. We conducted a general review of the literature to clarify the role of irradiation in the global management of ovarian cancers, particularly in recurrence.

Survey of current practices from an international task force for gynecological stereotactic ablative radiotherapy

Background

Stereotactic Ablative Radiotherapy (SABR) is an effective treatment that improves local control for many tumours. However, the role of SABR in gynecological cancers (GYN) has not been well-established. We hypothesize that there exists considerable variation in GYN-SABR practice and technique. The goal of this study is to describe clinical and technical factors in utilization of GYN-SABR among 11 experienced radiation oncologists.

Materials and methods

A 63 question survey on GYN-SABR was sent to 11 radiation oncologists (5 countries) who have published original research, conducted trials or have an established program at their institutions. Responses were combined and analyzed at a central institution.

Results

Most respondents indicated that salvage therapy (non-irradiated or re-irradiated field) for nodal (81%) and primary recurrent disease (91%) could be considered standard options for SABR in the setting of inability to administer brachytherapy. All other indications should be considered on clinical trials. Most would not offer SABR as a boost in primary treatment off-trial without absolute contraindications to brachytherapy. Multi-modality imaging is often (91%) used for planning including PET, CT contrast and MRI. There is a wide variation for OAR tolerances however small bowel is considered the dose-limiting structure for most experts (91%). Fractionation schedules range from 3 to 6 fractions for nodal/primary definitive and boost SABR.

Conclusions

Although SABR has become increasingly standard in other oncology disease sites, there remains a wide variation in both clinical and technical factors when treating GYN cancers. Nodal and recurrent disease is considered a potential indication for SABR whereas other indications should be offered on clinical trials. This study summarizes SABR practices among GYN radiation oncologists while further studies are needed to establish consensus guidelines for GYN-SABR treatment.

Stereotactic Body Radiation Therapy in Oligometastatic Ovarian Cancer: A Promising Therapeutic Approach

OBJECTIVE

Stereotactic body radiation therapy (SBRT) has been successfully used to treat oligometastases of several primary tumors, but few experiences have been described in patients with gynecological oligometastatic cancer, particularly in ovarian neoplasm. The aim of this study was to evaluate the role of this new radiotherapy modality in a series of oligometastatic ovarian cancer patients.

MATERIALS AND METHODS

Clinical records of patients affected by oligometastatic ovarian carcinoma treated with SBRT were reviewed.

RESULTS

Twenty-six patients with 44 metastatic lesions (lymph nodes, 63.6%; liver, 31.8%; and lung, 4.5%) treated with SBRT between January 2011 and May 2017 were analyzed. After a median follow-up period of 28.5 months (range, 6-86 months), 17 patients (65.4%) were still alive at time of analysis: 6 are without evidence of disease, 11 experienced a disease progression. Eight patients died of disease, 1 died because of an heart attack while being disease free. The median local control (LC) was not reached. One-, 2-, and 5-year LCs were 92.9%. Median progression-free survival was 19 months, with 1-year progression-free survival of 69.3% and 38% at 2 years, 19% at 5 years. Median overall survival was 64.5 months, with all patients alive after 1 year, 92.7% at 2 years, and 61.7% at 5 years. Five (11.3%) cases experienced G2 toxicity; most common adverse effect was nausea and vomiting (3 cases [6.8%]) followed by abdominal pain (2 cases [4.5%]). None of the patients had grade 3 or grade 4 acute or late toxicity.

CONCLUSIONS

In conclusion, SBRT is a feasible and safe approach for selected cases of oligometastatic ovarian cancer, with satisfactory results in terms of LC and disease free survival.

Salvage Curative-Intent Reirradiation Stereotactic Body Radiation Therapy for Isolated Pelvic and/or Paraortic Recurrences of Gynecologic Malignancies

PURPOSE

To determine the feasibility of stereotactic body radiation therapy (SBRT) for isolated nodal recurrences of gynecologic malignancies within a previously irradiated area.

METHODS AND MATERIALS

A retrospective review was performed on 20 patients who underwent 21 curative-intent reirradiation SBRT treatments for locoregional recurrences of gynecologic malignancies. Disease control and survival outcomes were analyzed with the Kaplan-Meier method and log-rank test. Treatment toxicities were graded according to Common Terminology Criteria for Adverse Events version 4.03.

RESULTS

All patients had an isolated pelvic, paraortic, or intra-abdominal nodal recurrence, with the exception of 1 patient who had a concurrent paraortic and right acetabulum metastasis, both of which were irradiated with SBRT. Primary sites included cervix (30.0%), uterus (55.0%), vulva (5.0%), vagina (5.0%), and ovary (5.0%). Median prior external beam radiation therapy dose was 45 Gy. Recurrences were in field in 14 (66.7%) and marginal in 7 (33.3%). SBRT was directed to the pelvis in 13 cases (61.9%) and to paraortic or celiac nodes in 8 (38.1%). The most common SBRT regimen was 40 to 45 Gy in 5 fractions (n = 12). At a median follow-up of 31.2 months, 3-year actuarial in-field local control, distant progression-free survival, and overall survival were 61.4%, 44.0%, and 51.9%, respectively. At the time of last follow-up, 9 (45.0%) patients remained alive without evidence of disease. Actuarial 3-year risk of grade ≥2 and grade ≥3 late toxicities was 38.1% and 14.3%, respectively.

CONCLUSIONS

SBRT for isolated pelvic or intra-abdominal recurrences of gynecologic malignancies within a previously irradiated field is feasible with an acceptable toxicity rate. With this approach, about half of patients achieved durable disease-free survival.

Stereotactic Body Radiation Therapy for Oligometastatic Ovarian Cancer: A Step Toward a Drug Holiday

PURPOSE

To evaluate stereotactic body radiation therapy (SBRT) for metachronous oligometastatic ovarian cancer patients in terms of local control, delay of systemic treatment, survival outcomes, and toxicity.

METHODS AND MATERIALS

Retrospective data collection from a single institution was performed. The inclusion criteria were as follows: (1) oligorecurrent or oligoprogressive disease in ovarian cancer patients during or after systemic therapy; (2) surgery or other local therapies not feasible; and (3) relative contraindication to systemic therapy for reasons such as unavailability of additional chemotherapy lines or refusal of the patient. Tumor response and toxicity were evaluated using the Response Evaluation Criteria in Solid Tumors and the Common Terminology Criteria for Adverse Events version 4.03, respectively. A new systemic therapy regimen was started after an SBRT treatment course in 57 of 109 cases (52.3%). Local progression-free survival, progression-free survival, and overall survival were calculated via the Kaplan-Meier method. The systemic treatment-free interval was calculated in cases without concomitant systemic therapy.

RESULTS

Between May 2012 and December 2016, 82 patients (156 lesions) underwent SBRT with a median dose of 24 Gy in 3 fractions. The median follow-up period was 17.4 months. Patients received a median of 3 systemic therapy regimens prior to SBRT. Concomitant systemic therapy was performed for 29 lesions (18.6%). Among 152 evaluable lesions, a complete radiologic response, partial response, stabilization, and progressive disease were observed in 91 (60%), 26 (17%), 24 (16%), and 11 (7%), respectively. No grade 3 or 4 acute or late toxicities were observed. The median systemic treatment-free interval after SBRT was 7.4 months, and 1 of 3 patients was disease free at 1 year after SBRT. The actuarial 2-year local progression-free survival, progression-free survival, and overall survival rates were 68%, 18%, and 71%, respectively. The pattern of failure was predominantly out of field.

CONCLUSIONS

SBRT for oligometastatic ovarian cancer showed good local control and a good toxicity profile. It might be an appealing alternative to other invasive local therapies to delay systemic therapy in the case of chemorefractory disease or intolerance to systemic agents.

Re-irradiation of cervical and endometrial cancer

PURPOSE OF REVIEW

Re-irradiation historically has been associated with unacceptable toxicity and limited benefit. Recent advances in radiotherapy can change the treatment paradigm to provide new salvage treatments for recurrences of cervical and endometrial cancer.

RECENT FINDINGS

Image-guided brachytherapy is an effective method for salvaging central pelvic recurrence, although it has resulted in 20-25% severe late toxicity. Pelvic sidewall disease is not accessible to brachytherapy, so a combined modality approach with radical surgery and intraoperative radiotherapy is an alternative approach. Stereotactic body radiotherapy (SBRT) now provides the option of radical re-irradiation with local control rates of 50-80% and a low incidence of severe late complications.

SUMMARY

Initial outcomes using SBRT and image-guided brachytherapy for re-irradiation of gynaecological cancer are encouraging. There has been good local control and acceptable toxicity. Further, large-scale studies are required to define optimal target doses and OAR limits.

Radiation Treatment in Women with Ovarian Cancer: Past, Present, and Future

Ovarian cancer is the most lethal of the gynecologic cancers, with 5-year survival rates less than 50%. Most women present with advanced stage disease as the pattern of spread is typically with dissemination of malignancy throughout the peritoneal cavity prior to development of any symptoms. Prior to the advent of platinum-based chemotherapy, radiotherapy was used as adjuvant therapy to sterilize micrometastatic disease. The evolution of radiotherapy is detailed in this review, which establishes radiotherapy as an effective therapy for women with micrometastatic disease in the peritoneal cavity after surgery, ovarian clear cell carcinoma, focal metastatic disease, and for palliation of advanced disease. However, with older techniques, the toxicity of whole abdominal radiotherapy and the advancement of systemic therapies have limited the use of radiotherapy in this disease. With newer radiotherapy techniques, including intensity-modulated radiotherapy (IMRT), stereotactic body radiotherapy (SBRT), and low-dose hyperfractionation in combination with targeted agents, radiotherapy could be reconsidered as part of the standard management for this deadly disease.

Clinical Outcomes for Stereotactic Ablative Radiotherapy in Oligometastatic and Oligoprogressive Gynecological Malignancies

Objectives

We report single-institution clinical outcomes of women treated with stereotactic ablative radiotherapy (SABR) for oligometastatic or progressive gynecological malignancies.

Materials and Methods

From 2009 to 2015, 47 lesions from 28 patients were treated with SABR and retrospectively analyzed. All patients had oligometastatic (93%) or oligoprogressive (7%) disease. Primary cancer diagnoses were 15 ovarian, 8 endometrial, 2 cervical, 2 vaginal, and 1 uterine carcinosarcoma. Treatment was delivered using a median of 5 fractions to a median total dose of 40 Gy. Targets were grouped by treatment site and assessed for response using Response Evaluation Criteria in Solid Tumors v1.1. Mean biologically effective dose and pre-SABR tumor size were compared with response. Progression-free survival (PFS) was determined using Kaplan-Meier analysis, and toxicity outcomes were graded using Common Terminology Criteria for Adverse Events version 4.03.

Results

Median follow-up was 12.8 months. Target locations were 17% liver, 21% lung, 17% paraaortic node, 26% other node, and 19% pelvic soft tissue. After treatment, 34% of targets were stable (SD), 32% had a partial response (PR), 17% had a complete response (CR), and 17% had progressive disease (PD). No failures occurred in lung or nodal targets. Mean ± standard deviation pre-SABR tumor diameter was 24 ± 22 mm. There was a significant difference in mean size between lesions that had a favorable (SD, PR, and CR) versus unfavorable response (PD) (17.2 vs 57.6 mm,P= 0.0044). Lesions that responded favorably were also more likely to have received a higher biologically effective dose (79.0 vs 59.6 Gy,P= 0.027). Median PFS was 10.8 months, and 1 patient experienced grade 3 toxicity.

Conclusions

The SABR is a safe and effective local treatment modality in patients with oligometastatic gynecological disease. Distant progression remains the primary mode of failure in this patient population. In carefully selected patients, a combination of systemic treatment and SABR may offer long-term PFS.

High-dose-rate interstitial brachytherapy for the treatment of high-volume locally recurrent endometrial carcinoma

PURPOSE

Limited therapeutic options are available for the treatment of locally recurrent endometrial carcinoma. Our objective was to report an institutional experience using interstitial brachytherapy (IBT) to treat significant recurrent endometrial carcinoma, including previously irradiated disease.

METHODS AND MATERIALS

Between December 2004 and September 2012, 40 patients with high-volume locally recurrent endometrial cancer were treated by high-dose-rate IBT (± external beam radiation therapy EBRT). Sixteen patients had prior radiotherapy: EBRT alone (n = 5), intracavitary brachytherapy alone (n = 3), or EBRT with intracavitary brachytherapy boost (n = 8). Actuarial outcome rates were calculated using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Median followup interval was 18 months. Median disease-free interval was 61 months. Actuarial local control, progression-free survival (PFS), and overall survival were 74% and 60%, 70% and 51%, and 83% and 72% at 12 and 24 months, respectively. p-Values for local control, progression-free survival, and overall survival between patient who had prior RT (n = 16) to no prior RT (n = 24) were p = 0.38, 0.32, and 0.90, respectively. Acute toxicities include Grade 1-2 pain (5%), genitourinary (7%), gastrointestinal (12%), soft tissue (5%), and dermatologic (12%). Four patients observed late Grade 3-4 toxicities, including rectal bleeding/fistula and soft tissue necrosis.

CONCLUSIONS

High-dose-rate IBT is an effective treatment for locally recurrent endometrial carcinoma with an acceptable toxicity profile. Outcomes are similar between previously irradiated and nonirradiated patients. In women who have received prior radiotherapy and are often considered for palliative treatment, interstitial brachytherapy is a potentially curative option.

Challenges of Using High-Dose Fractionation Radiotherapy in Combination Therapy

Radiotherapy is crucial and substantially contributes to multimodal cancer treatment. The combination of conventional fractionation radiotherapy (CFRT) and systemic therapy has been established as the standard treatment for many cancer types. With advances in linear accelerators and image-guided techniques, high-dose fractionation radiotherapy (HFRT) is increasingly introduced in cancer centers. Clinicians are currently integrating HFRT into multimodality treatment. The shift from CFRT to HFRT reveals different effects on the tumor microenvironment and responses, particularly the immune response. Furthermore, the combination of HFRT and drugs yields different results in different types of tumors or using different treatment schemes. We have reviewed clinical trials and preclinical evidence on the combination of HFRT with drugs, such as chemotherapy, targeted therapy, and immune therapy. Notably, HFRT apparently enhances tumor cell killing and antigen presentation, thus providing opportunities and challenges in treating cancer.

The development of stereotactic body radiotherapy in the past decade: a global perspective

In the past 10 years, there has been an exponential increase in the incorporation of stereotactic body radiotherapy, also known as stereotactic ablative radiotherapy, into the armamentarium against various types of cancer in different settings worldwide. In this article in the 10th year anniversary issue of Future Oncology, representatives from the USA, Canada, Japan, Germany, The Netherlands, Australia and Singapore will provide individual perspectives of the development of stereotactic body radiotherapy in their respective countries.