At the Colorado Center for Gynecologic Oncology, we are are interested in new studies that can benefit our patients. With improved radiation for therapy for ovarian cancer, we can target diseases in patients with ovarian cancer to result in a better outcome. If you would like more information, you can contact us at (303) 955-7574.
New radiation therapy technologies that more accurately target disease and spare surrounding tissue are being explored in patients with ovarian cancer.
Epithelial ovarian cancer is the most lethal of the gynecologic cancers, with a 5-year survival rate less than 50%. Each year, an estimated 22,000 women are diagnosed with this disease, and 14,000 women die from it, said Emma Fields, MD, of Virginia Commonwealth University in Richmond, and colleagues, reviewing the topic in Frontiers in Oncology.
“With aggressive therapy at diagnosis, including surgery and platinum-based chemotherapy, more than 80% of women diagnosed with advanced disease will have an initial complete response. Unfortunately, these responses are infrequently durable and the majority of women with ovarian cancer develop recurrent disease, which is typically incurable,” Fields and colleagues said. “Responses to subsequent chemotherapeutic regimens shorten in duration over time due to progressive development of resistance to platinum-based chemotherapy. Novel treatment strategies are urgently needed in order to improve survival.”
Although ovarian cancer is considered to be radiosensitive, radiation therapy options have been limited, the authors noted. For example, whole pelvic radiation is largely ineffective because ovarian cancer is rarely confined to the pelvis. Whole abdominal radiotherapy was used in the pre-chemotherapy era, but toxicity was high, particularly with wide-field irradiation. “High rates of both acute and late toxicity, particularly gastrointestinal, resulted in the abandonment of radiation in this disease, particularly when cisplatin was confirmed to be a highly active systemic agent,” Field’s group stated.
“However, improved radiation techniques with lower toxicity have led to a renewed interest in the use of radiation therapy for metastatic cancers for many disease sites including ovarian cancer.” These techniques, which have shown efficacy in other cancers, include intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT).
Intensity-modulated radiation therapy has replaced three-dimensional conformal radiotherapy for treating complex tumors in close proximity to organs at risk. IMRT has primarily been used in prostate, anal, and head and neck cancers, and the technique uses 3-D computed tomography or magnetic resonance imaging in conjunction with a computer algorithm to determine a dose intensity pattern that best conforms to the patient’s tumor shape, Fields and colleagues explained.
A research team led by Shi-Gao Huang, MD, of the University of Macau in Taipa, China, recently conducted a study of PET/CT-guided IMRT in 42 patients with stages III/IV recurrent ovarian cancer. These included patients who had undergone chemotherapy and surgery as well as those who had received either surgery or chemotherapy alone, the researchers wrote in Oncology Letters.
The progression-free survival (PFS) rate was 67% at 1 year, 33% at 2 years, and 21% at 3 years; median PFS was 20 months. The rates of overall survival were 74%, 64%, and 52%, respectively. “For patients with advanced ovarian cancer, particularly for patients unable to undergo surgery or chemotherapy, 18F‑FDG PET/CT‑guided IMRT is a safe and effective treatment method, and it may be considered as an equally effective treatment option,” Huang’s group wrote.
Volumetric-modulated arc therapy is a more advanced form of IMRT, Julia Fehniger, MD, of New York University in New York City, and colleagues, wrote in a case report in Gynecologic Oncology Reports. The technique delivers radiation on a linear accelerator using a cone beam that continuously rotates around the patient. Each rotation is called an arc, and one or more arcs might be used. During each arc, the beam is continuously shaped by a multi-leaf collimator. In addition, the dose rate and gantry speed are optimized to generate a highly conformal dose.
Fehniger’s group added a new twist to VMAT, using small, implanted transponders to more accurately guide the radiation dose. These transponders were tiny glass capsules measuring 1.85 mm x 8.7 mm and containing an electronic circuit, which were then injected into the target tissue. “Data is transmitted continuously during treatment to a monitoring system that alerts the radiation therapist if the target position exceeds a pre-specified distance from the isocenter, allowing for real-time adjustment of a patient’s position to more precisely deliver radiation therapy,” the researchers explained.
The case they described was that of a 52-year-old woman with ovarian clear cell carcinoma. She underwent surgery and platinum-based chemotherapy. During surgery, a right ovarian mass was found. A secondary surgery resected most of this mass, but a 5 mm piece remained, densely adherent to the right ureter and hypogastric artery. Fehniger’s team treated this small remaining mass with transponder-guided VMAT.
“The patient tolerated radiation therapy well and did not describe any radiation-related toxicities either during treatment or in post-treatment surveillance. The patient has no evidence of disease 18 months after surgery,” Fehniger et al. wrote.
“Although radiation therapy is not standardly utilized in the treatment of recurrent ovarian cancer, it may have increased efficacy in tumors with clear cell histology. While concerns about the toxicities associated with radiation for recurrent ovarian cancer have limited its use in the past, improved techniques like IMRT and VMAT allow for the delivery of localized radiation therapy while sparing surrounding normal tissue.”