Initial physical examination should include a comprehensive gynecologic exam with specific attention paid to noting the local extent of the disease and inguinal nodal involvement. In GOG 37, 23.8 % of patients with clinically enlarged lymph nodes were found to have no evidence of disease on pathologic assessment, while 23.9 % of patients with a normal exam were found to have occult metastatic disease. Thus physical examination is neither sensitive nor specific in identifying the extent of nodal involvement. CT or PET-CT is therefore essential in workup and treatment planning.

Extrapolating from other pelvic malignancies, most prominently anal cancer, where the role of PET-CT is well established, we recommend incorporating PET-CT-based planning for all vulvar patients to increase the sensitivity of identifying nodal disease that would otherwise be undetected by the combination of physical exam and CT imaging (Cotter et al. 2006).

The use of gadolinium-enhanced pelvic MRI with and without water-based endoluminal vaginal gel is important in locally advanced disease to evaluate the relationship between tumor and functionally integral normal tissues such as the musculature of the anal sphincter and vagina that preclude surgical resection (see Fig. 3).

When disease involves the vagina, a gold fiducial marker is placed during in-office speculum examination to identify the vaginal extent of disease aiding in GTV definition and daily setup.

CT or PET-CT simulation in the supine position with the lower extremities abducted (“frog-legged”) and immobilized in a vacuum-evacuated device to assure reproducibility in setup. By abducting the lower extremities to the maximal extent allowable by the scanner, the dose to the medial thigh and groin folds is minimized.

In order to assist in delineation of the tumor, radiopaque wire is used to identify areas of gross disease or the postoperative tumor bed (see Fig. 4).

CT or PET-CT simulation using 3–5 mm thickness with IV and oral contrast. Oral contrast assists in the small bowel and rectum visualization, while the IV contrast aids in visualization of the vasculature structures for nodal contouring. We typically recommend a simulation scan from at least the L2 through the mid thigh. The isocenter is typically placed in the center of the pelvis if treating lymph nodes. In comparison, it is typically placed in the vulva at the level of pubic symphysis if targeting only the vulva.

If the vagina is involved (and thus to be included in CTV1 as described below), we suggest performing the simulation with a full and empty bladder to create an ITV (internal target volume) for the vaginal region. It is recommended that all vulvar patients be treated with a full bladder and empty rectum irrespective of vaginal involvement. On the day prior to simulation, patients are instructed to take a fleet enema and are re-simulated if rectal distention is >3.0–3.5 cm since an empty rectum represents the most conservative posterior location for rectal filling effects on interfraction motion.

We avoid the use of a vaginal obturator or marker as these devices distort anatomy and create non-reproducible anatomical deformation of the pliable vaginal mucosa. Additionally, the devices displace the vagina posteriorly, creating a situation prone to geographic miss.

A customized bolus of 0.5–1 cm thickness is usually created for the vulvar region at the time of treatment planning and is used for daily treatments. Separate plans are generated with and without bolus at the time of initial IMRT planning, such that should the patient develop a brisk skin reaction, treatment can be continued without bolus and no attendant treatment interruption. Additionally a 1–2 cm thick bolus structure is extended in air for IMRT plan optimization only, which serves to extend the isodose line beyond the skin for flash to account for edema and swelling (see Fig. 5). The difference in monitor units with and without bolus should be minimal.

Patients are typically set up with a combination of daily KV and CBCT imaging. Daily kV imaging is used to reduce interfraction motion based upon the bony anatomy or to fiducial markers placed at the vaginal extent of disease if present. For boost CBCT daily would be preferred for daily localization and matching with the soft tissue.

The primary GTV includes all gross disease on physical examination and imaging. For pelvic and inguinal, GTV includes all lymph nodes ≥1 cm in the short axis, those with a necrotic center and/or PET avidity (see Table 1 and 2).