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Pelvic Radiotherapy May Benefit Some Women With Ovarian Clear Cell Adenocarcinoma

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Key Points

  • Clear cell adenocarcinoma is a relatively rare yet aggressive subtype of epithelial ovarian cancer, and its recurrence patterns remain unclear.
  • There was no significant difference in the cumulative incidence of pelvic tumor recurrence with and without radiotherapy, according to the results of a small retrospective study at a single institution.
  • According to the study investigators, the use of radiotherapy yielded a trend toward reduction in the cumulative incidence of pelvic tumor recurrence at 5 and 8 years, and prospective studies with sufficient statistical power are warranted.

 

Adjuvant radiotherapy may play a role in the management of ovarian clear cell adenocarcinoma, which appears to be less prone to peritoneal dissemination than other subtypes, according to the results of a small retrospective study reported by Macrie et al in the International Journal of Gynecological Cancer. This rare carcinoma seems to have a greater tendency to recur in the pelvis than do other subtypes of epithelial ovarian tumors, but larger prospective studies are needed to validate these findings on pelvic radiotherapy in this patient population.

The standard therapeutic regimen for women with epithelial ovarian cancer is intense, consisting of comprehensive surgical staging, optimal cytoreduction, and adjuvant platinum-based chemotherapy. However, outcomes have remained relatively poor in these patients, with ovarian cancer remaining the fifth most common cause of cancer death in women.

Clear cell adenocarcinoma of the ovaries is a distinct yet relatively rare subtype of epithelial ovarian cancer, accounting for between 5% and 10% of all ovarian cancers. This aggressive subtype is characterized by gross confinement to the pelvis at diagnosis and chemoresistance. Unlike for the broader category of epithelial ovarian cancers, for clear cell adenocarcinoma, recurrence patterns remain unclear, as does the role of radiotherapy.

Study Details

To shed more light on the use of radiotherapy in ovarian clear cell adenocarcinoma, Macrie and colleagues conducted a retrospective review of tumor recurrence in patients with ovarian clear cell adenocarcinoma at a single institution (from 1989 to 2012). The inclusion criteria were histologic diagnosis of pure clear cell adenocarcinoma of the ovaries, International Federation of Gynecologic and Obstetrics staging of stage I to IIIC disease, surgical staging, and use of adjuvant or neoadjuvant chemotherapy. A total of 56 patients (with a median age of 51 years) met the study eligibility criteria and were included in the final analysis.

All patients except one were treated with a platinum-based chemotherapy regimen, and most of them received a combination of intravenous carboplatin and paclitaxel. Of the 40 patients who had early-stage disease, 6 underwent adjuvant pelvic radiotherapy. The majority of patients in the study (89%) did not receive pelvic radiotherapy.

In addition, the investigators estimated the cumulative incidences of pelvic tumor recurrence at 3-, 5-, and 8-year endpoints. These incidences for patients receiving and for those not receiving radiation therapy were compared.

Similar Cumulative Incidences of Pelvic Tumor Recurrence

The median follow-up was 39 months. Tumor recurrence occurred in 7 of the 40 patients with early-stage disease (17.5%) and 7 of the 16 patients with advanced-stage disease (43.8%). For the entire study group, eight patients (14.2%) had tumor recurrence locally within the pelvis, and six patients (10.7%) experienced first tumor recurrence outside the pelvis.

The cumulative incidence of pelvic tumor recurrence was 28% at 3 years, 39% at 5 years, and 43% at 8 years. In a comparison of those receiving and those not receiving radiotherapy, there was no significant difference in 3-, 5-, and 8-year cumulative incidences of pelvic tumor recurrence in those who received radiotherapy (20%, 20%, and 20%, respectively) and in those who did not (10%, 22%, and 30%, respectively).

Closing Thoughts

These study results are generally in agreement with recurrence rates from other representative series of ovarian clear cell adenocarcinoma, according to the investigators. However, the rate of first tumor recurrence involving the pelvis seen in this study was higher than that seen in early-stage epithelial ovarian cancer, they added, supporting the notion that this subtype may have a predilection for pelvic failure that exceeds that of other histologic subtypes. Furthermore, the investigators mentioned that several clinical series have shown that adjuvant radiotherapy may be of greater value in ovarian clear cell adenocarcinoma than in other histologic subtypes of epithelial ovarian cancer.

“In the present study, the use of pelvic radiotherapy yielded a trend toward reduction in cumulative incidence of pelvic tumor recurrence at 5 and 8 years. Although by no means definitive, these data contribute to a growing body of literature supporting the clinical use of adjuvant radiotherapy in the management of ovarian clear cell adenocarcinoma,” concluded the investigators.

William Small Jr, MD, of the Department of Radiation Oncology, Stritch School of Medicine, Loyola University Chicago, Cardinal Bernardin Cancer, Maywood, Illinois, is the corresponding author of this article in the International Journal of Gynecological Cancer. The authors reported no potential conflicts of interest.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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