Treatment Positioning in Vulvar Cancer Radiation Therapy

Vulvar cancer is a rare tumor with a prevalence of about 3-5% of gynecological malignancies with squamous cell carcinoma being the most common histopathologic subtype. It is more common among elderly and postmenopausal women.

Surgery is the cornerstone for the management of patients with early stage vulvar cancer. Radiotherapy is an integral part of the management of vulvar cancer both in the definitive and adjuvant settings.

Several studies have shown that intensity modulated radiotherapy IMRT is associated with better locoregional control compared with 3-dimensional conformal radiotherapy 3DCRT. In addition, it is associated with dosimetric advantage and better sparing of the organs at risk.

Historically, frog-leg position was the standard to provide better access for electron boost in conventional era. After evolution of inverse planning, electron boost is not further needed. Some centers have adopted straight-leg position.

There is paucity of literature regarding vulvar cancer in general and there is lack of data addressing radiation therapy treatment position specifically.

The study investigators will conduct a prospective study on patients with non-metastatic vulvar cancer who will receive radiation treatment using Volumetric Arc Therapy (VMAT) modality with curative intent. Our aim is to compare straight-leg versus frog-leg position in terms of RTOG acute skin toxicity. Also, the investigators will evaluate if positioning has an impact on the total treatment time and deviation on Cone Beam CT (CBCT) that might warrant re-simulation and consequently re-planning.

If both positions proved to be similar in terms of skin toxicity, then the investigators will adopt supine position in the treatment of all patients with vulvar cancer. It will be more comfortable position, and so more reproducible and this reproducibility will be reflected on better treatment outcomes.