Fractionated stereotactic radiotherapy boost for gynecologic tumors: An alternative to brachytherapy?

doi:10.1016/j.ijrobp.2004.09.028

International Journal of Radiation OncologyBiologyPhysics

Volume 62, Issue 1, 1 May 2005, Pages 118-124

https://doi.org/10.1016/j.ijrobp.2004.09.028 Get rights and content

Purpose: A brachytherapy (BT) boost to the vaginal vault is considered standard treatment for many endometrial or cervical cancers. We aimed to challenge this treatment standard by using stereotactic radiotherapy (SRT) with a linac-based micromultileaf collimator technique.

Methods and Materials: Since January 2002, 16 patients with either endometrial (9) or cervical (7) cancer have been treated with a final boost to the areas at higher risk for relapse. In 14 patients, the target volume included the vaginal vault, the upper vagina, the parametria, or (if not operated) the uterus (clinical target volume [CTV]). In 2 patients with local relapse, the CTV was the tumor in the vaginal stump. Margins of 6–10 mm were added to the CTV to define the planning target volume (PTV). Hypofractionated dynamic-arc or intensity-modulated radiotherapy techniques were used. Postoperative treatment was delivered in 12 patients (2 × 7 Gy to the PTV with a 4–7-day interval between fractions). In the 4 nonoperated patients, a dose of 4 Gy/fraction in 5 fractions with 2 to 3 days’ interval was delivered. Patients were immobilized in a customized vacuum body cast and optimally repositioned with an infrared-guided system developed for extracranial SRT. To further optimize daily repositioning and target immobilization, an inflated rectal balloon was used during each treatment fraction. In 10 patients, CT resimulation was performed before the last boost fraction to assess for repositioning reproducibility via CT-to-CT registration and to estimate PTV safety margins around the CTV. Finally, a comparative treatment planning study between BT and SRT was performed in 2 patients with an operated endometrial Stage I cancer.

Results: No patient developed severe acute urinary or low-intestinal toxicity. No patient developed urinary late effects (>6 months). One patient with a vaginal relapse previously irradiated to the pelvic region presented with Grade 3 rectal bleeding 18 months after retreatment. A second patient known to suffer from irritable bowel syndrome presented with Grade 1 abdominal pain after treatment. The estimated PTV margins around the CTV were 9–10 mm with infrared marker registration. External SRT succeeded in improving dose homogeneity to the PTV and in reducing the maximum dose to the rectum, when compared to BT.

Conclusion: These results suggest that the use of external SRT to deliver a final boost to the areas at higher risk for relapse in endometrial or cervical cancer is feasible, well tolerated, and may well be considered an acceptable alternative to BT.

Introduction

Radiation therapy (RT) is commonly used in the treatment of endometrial and cervical cancer. Patients are frequently treated with external photon irradiation to the whole pelvis (WPRT), followed by intracavitary brachytherapy (BT), either low-dose rate or high-dose rate (HDR), to a boost volume usually including the vaginal vault and, in nonoperated patients, the uterus and parametria. Stereotactic radiotherapy (SRT) may be used to treat the final boost volume in endometrial/cervical cancer patients with time-dose fractionation schedules similar to those with HDR-BT. However, SRT offers several advantages over HDR-BT, including simplified radiation protection, no need for hospitalization, no anesthesia, no narcotics, and a potential improvement in target dose distribution.

Stereotactic RT to relatively small pelvic targets has been made possible thanks to new treatment delivery techniques (i.e., dynamic-arc treatment and intensity-modulated radiotherapy [IMRT]) and to the availability of highly accurate immobilization and repositioning systems. Optimal repositioning with infrared (IR) metallic body markers and an inflatable rectal probe has been recently reported for prostate cancer patients (1).

The purpose of this study was to challenge the BT standard for gynecologic tumors by using high-precision linear accelerator-based SRT with micromultileaf collimation. We aimed to assess tolerance and repositioning reproducibility of this new treatment approach, and to evaluate the dose distributions achieved by SRT in the target and surrounding organs at risk (OARs) compared with those attainable using HDR-BT.

Section snippets

Patients

Since January 2002, 16 consecutive women with either cervical cancer (7 patients) or endometrial cancer (9 patients) have been treated with a final boost to the areas at higher risk for relapse. Patient ages ranged from 33 to 71 years (median, 53 years). Patient, tumor, and treatment characteristics are summarized in Table 1. Four cervix cancer patients (2 Stage IB2, 1 Stage IIB, and 1 Stage IIIB) received adjuvant chemotherapy (cisplatin and 5-fluorouracil). WPRT was delivered to 12 patients

Results

After a 12.6-month median follow-up interval (range, 6–26 months), only 1 patient with cervical cancer (Stage I) treated postoperatively developed a central pelvic recurrence 12 months after RT. Surgical salvage has been undertaken, and the patient is presently alive with disease.

Treatment was well tolerated, resulting in no treatment interruptions. Acute and late reactions are reported in Table 2. No patient developed Grade 3 toxicity. Grade 1 acute sexual toxicity was observed in 4 patients

Discussion

Extracranial external SRT is a novel treatment technology that aims to deliver focused and sharply conformal beams to relatively small targets in the pelvis for endometrial or cervical carcinomas. Such small targets are usually the vaginal vault (in operated endometrial tumors), the primary tumor and parametria (in nonoperated cervical cancers), and the vaginal stump relapses (after surgery or RT in both endometrial and cervical tumors). With the present study, we have been able to show that

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Brachytherapy: A critical component of primary radiation therapy for cervical cancer: From the Society of Gynecologic Oncology (SGO) and the American Brachytherapy Society (ABS)
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Brachytherapy is well-established as an integral component in the standard of care for treatment of patients receiving primary radiotherapy for cervical cancer. A decline in brachytherapy has been associated with negative impacts on survival in the era of modern EBRT techniques. Conformal external beam therapies such intensity modulated radiation therapy (IMRT) or stereotactic body radiation therapy (SBRT) should not be used as alternatives to brachytherapy in patients undergoing primary curative-intent radiation therapy for cervical cancer. Computed tomography or magnetic resonance image-guided adaptive brachytherapy is evolving as the preferred brachytherapy method. With careful care coordination EBRT and brachytherapy can be successfully delivered at different treatment centers without compromising treatment time and outcome in areas where access to brachytherapy maybe limited.
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To summarise and evaluate the current literature in gynaecological tumours treated with stereotactic ablative body radiotherapy (SABR) through a systematic review using the Preferred Reported Items for Systematic Reviews and Meta-analysis (PRISMA) guideline.
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Clinical investigationsEndometriumFractionated stereotactic radiotherapy boost for gynecologic tumors: An alternative to brachytherapy?

Introduction

Section snippets

Patients

Results

Discussion

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Radiat Oncol

Int J Radiat Oncol Biol Phys

Radiother Oncol

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Clinical investigations
Endometrium
Fractionated stereotactic radiotherapy boost for gynecologic tumors: An alternative to brachytherapy?