The three histological subtypes are mainly carcinosarcoma, leiomyosarcoma (LMS), and endometrial stromal sarcoma (ESS). Uterine carcinosarcomas, also known as malignant mixed mesodermal tumors (MMT) or malignant mixed Mullerian tumors (MMMT), have both malignant epithelial and malignant mesenchymal components. Of the three histologies, uterine carcinosarcomas are the most common followed by leiomyosarcomas and then endometrial stromal sarcomas [4]. In recent years, carcinosarcoma has been reclassified and moved from the uterine sarcoma group to endometrial carcinomas of high-risk type [5]. Though the benefits of postoperative radiotherapy and chemotherapy are still under debate, the role of radiotherapy is more defined in carcinosarcoma compared to LMS and ESS [1, 6–9].

In literature, there are many retrospective studies with contradicting results and inferences regarding the efficacy of adjuvant radiotherapy in improving local control rates and its impact on overall survival. The two large SEER (Survey, Epidemiology, and End Results) cancer registries showed lack of overall survival benefit in stage I–III carcinosarcoma, and the one by Smith et al. showed an overall survival benefit in stage IV disease [10, 11].

Uterine sarcomas usually metastasize hematogenously early in their course, leading to a lack of survival benefit by pelvic radiotherapy. Sampath et al. reported a study of 3,650 women from USA and concluded that adjuvant radiotherapy does not have overall survival benefit but confers a 53 % reduction in the risk of locoregional failure at 5 years. The 5-year actuarial locoregional failure-free survival was 90 % vs. 80 % (P < 0.05), in favor of adjuvant radiotherapy [12].

Sorbe et al. reported a large population-based study of 322 patients of primary uterine carcinosarcomas. Prophylactic pelvic irradiation and/or chemotherapy was used postoperatively in large majority of patients. Radiotherapy (external beam therapy followed by brachytherapy) was given in 204 cases (63 %). The locoregional recurrence rate in stage I–II tumors was lower (though not statistically significant) in patients who received adjuvant radiotherapy compared to surgery alone (8 % vs. 19 %; p = 0.103). Addition of radiotherapy plus chemotherapy resulted in a superior overall and recurrence-free survival compared with patients treated with chemotherapy alone or no adjuvant therapy (p = 0.000001). This effect on survival was evident across all stages, stages I–II ( p = 0.032) and stages III–IV (p = 0.000001) [13].

In the Gynecological Oncology Group study by Major et al., it was seen that addition of pelvic radiotherapy to surgery (at the discretion of treating physician) was associated with lower local failure rate, 17 % (43 out of 182) compared with surgery alone 24 % (20 out of 119) but with higher distant failures [2].

Whole abdominal radiation also does not seem to be effective in controlling pelvic failures or improving overall survival as seen in phase III randomized trial by GOG [14]. This could be because of lower doses of radiotherapy used in this study, i.e., 30 Gy compared to 45–50 Gy which is routinely used.

The recently reported EORTC-GCG is a landmark phase III trial addressing the utility of adjuvant pelvic RT for all subtypes of uterine sarcomas. All the 224 patients underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy and washings, but nodal sampling was optional. They were randomized to pelvic RT of 50.4 or observation. There was statistically significant reduction in local failure in patients who received adjuvant radiotherapy (14 vs. 24; p = 0.004) but no improvement in overall or progression-free survival [15]. This benefit was limited to patients with histology of carcinosarcomas but not in leiomyosarcomas. Besides this, many other studies also report a better local control with the use of adjuvant radiotherapy [16]. Recent Cochrane meta-analysis published in 2013 evaluated the effectiveness and safety of adjuvant radiotherapy in the management of uterine carcinosarcoma. It included five randomized controlled trials and radiotherapy to the abdomen were not associated with improved survival [17].

These are rare but challenging tumors with a poor prognosis. They occur most commonly around or shortly after the menopause. Like carcinosarcomas, they also have a high metastatic potential. In a retrospective study of 208 patients, Giuntoli et al. reported a significantly better local control (p = 0.011) and a trend (P = 0.056) for improved cause-specific survival in the patients who underwent adjuvant pelvic radiotherapy [18]. Another retrospective study of 147 patients by Madhavi et al. reported a better local control with adjuvant RT (18 % vs. 49 %; P = 0.02). The 5-year survival receiving adjuvant radiotherapy was significantly superior to those who did not receive radiotherapy (70 % vs. 35 %), but this survival advantage was lost at the extended follow-up at 90 months.

A large population-based study by Garg et al. of 819 women collected from SEER database did not report any survival advantage with RT though there were more advanced tumors in the RT group [19, 20].

The retrospective study by Sampath et al. also showed that patients receiving adjuvant RT had significantly reduced local failure (2 % vs. 16 %, p < 0.05) [12]. But in the EORTC trial, patients with LMS histology who received RT had significantly higher rates of distant metastasis (54 % vs. 33 %); therefore, authors concluded that RT should not be given in this group of patients [15]. This could be due to RT leading to a better local control in the pelvis with the distant metastasis being more evident. Therefore, for uterine leiomyosarcomas, RT should be reserved for select cases till future trials give level I evidence.