60 y/o F with FIGO Stage IIIA (pT2N1aM0) vulvar SCC s/p radical vulvectomy and bilateral groin dissections with positive deep and distal urethral margins, LVSI, and a 4mm R inguinal lymph node

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Technique: She was treated postoperatively with concurrent chemoradiation with weekly cisplatin using IMRT

Dose:

  • She received 45 Gy to the bilateral inguinofemoral, obturator, internal and external iliac LNs.
  • She then received sequential boosts of 54 Gy to the positive right inguinofemoral nodal basin and 59.4 Gy to the primary vulvar operative bed and positive urethral margin in 33 fractions.

Simulation:

  • Immobilized on a wing board in frog-legged supine position.
  • Radiopaque wires delineated vulvar operative bed.
  • BB placed on urethra (positive margin) and vaginal introitus.
  • 1 cm bolus over operative bed.
  • Comfortably full bladder.
  • IGRT with daily CBCT.

 

Case contributed by the University of Louisville

IMRT Contours per Vulvar Consensus Guidelines, NRG Oncology/RTOG 0921, and Female RTOG Normal Pelvis Atlas.

CTV_59.4: Entire operative bed (wires define borders).

  • Close or positive margins should be well within CTV (>2 cm from edge).
  • Fiducial markers may help identify sites of close/positive margins.
  • Vulva post-op RT dosing:
    • 60-70 Gy: Gross disease
    • 54-60 Gy: Positive/close margins
    • 45-50 Gy: Negative margins

CTV_ 54: Involved right inguinal nodal basin.

  • Pre-operative PET/CT imaging was fused for target volume delineation of this region.

CTV_45: Bilateral inguinofemoral, obturator, internal and external iliac LNs.

  • LN RT dosing:
    • 60-70 Gy: Gross/unresectable LNs
    • 54-65 Gy: ECE
    • 50-55 Gy: Positive LNs
    • 45-50 Gy: Clinically/radiographically negative LNs
  • Treat the “echelon above” the highest involved LN.
  • LN CTV coverage should include same LN regions on either side.

PTV_45-59.4: CTV + 7mm margin (trim 3-5 mm from non-target skin).

LN drainage echelons:

  • 1st – superficial inguinofemoral
  • 2nd – deep inguinofemoral
  • 3rd – external iliac
  • Clitoral lesions may drain directly to pelvic LNs.
  • If posterior vaginal wall involvement, consider coverage of pre-sacral LNs (S1-S3).
  • If anal involvement, consider mesorectal and pre-sacral LNs.

Adjuvant RT indications:

  • Primary vulvar site:
    • Close/positive margin (<8 mm, dVIN, Lichen sclerosis), LVSI, DOI > 5mm, tumor size, diffuse/spray histology.
  • Groins and Pelvis:
    • Any positive nodes (Cat 1 if ≥ 2 positive nodes or ECE).
    • Completion lymphadenectomy preferred prior to RT if >2 mm metastasis on SLNB.
    • See GROINSS-VII/GOG 270.