78 y/o F with unresectable Stage IIIB squamous cell carcinoma of the left labia (cT3N2bM0) treated with definitive chemoradiation.

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Rx:

  • Treated with definitive chemoradiation.
  • Entire vulva, bilateral inguinal and pelvic lymph nodes to 45 Gy in 25 fractions with IMRT. 
  • Simultaneous integrated boost to 57.5 Gy in 25 fractions to gross inguinal lymph nodes and 50 Gy in 25 fractions to primary tumor and inguinal nodal regions.
  • Sequential boost of 16 Gy in 8 fractions to primary tumor (cumulative 66 Gy in 33 fractions). 

Chemotherapy:

  • Patients treated with definitive radiation should be offered concurrent chemotherapy unless early stage (e.g. T1N0M0 and select, <4 cm T2N0M0) and otherwise not a surgical candidate.
  • She received concurrent weekly cisplatin (preferred), but can consider cisplatin with fluorouracil or fluorouracil with mitomycin C.

Sim/Plannning:

  • Sim with immobilization device, supine, in frog leg position to reduce inguinal skin folds. Place wires to define GTV and radio-opaque BBs at anus and urethra to aid in planning.
  • Simulate and treat with full (to reduce bowel dose) or neutral bladder, depending on patient comfort and reproducibility. 
  • Superflab bolus placed over vulva daily (0.5 cm) and removed once brisk skin reaction (before moist desquamation).
  • TLDs placed beneath bolus around vulvar GTV for first 3 fractions to assess average surface dose; bolus was adjusted as necessary to ensure adequate skin dose. Treated with neutral bladder.  
  • Consider re-simulation for primary tumor boost if significant tumor shrinkage. 
  • If vaginal, rectal or urethral involvement, include 1-2cm margin of these structures in the 50 Gy vulvar CTV.

Notes:

  • Patient had prior hysterectomy and presents fluid in the cul-de-sac

 

Case contributed by Emory University

Contours (per GOG-0279 Protocol and Gaffney IJROBP 2016):

GTV

  • GTVn = Gross nodal disease seen on imaging.
  • GTVp = Gross primary disease seen on imaging and exam (wire around tumor at time of sim)

CTV_4500

  • Vulvar CTV (CTVp): entire vulva up to skin surface including inferior pre-pubic fat
  • Nodal CTV (CTVn):  Vessels with 7 mm margin cropped out of muscle and bone
    • Pelvic lymph nodes, including obturator nodes, bilateral internal and external iliac nodes up to distal common iliac vessel (at bifurcation of external and internal iliac vessels)

PTV_4500

  • CTV_4500 + 5 mm margin
  • Cropped 3 mm from skin (except at vulva)

PTV_5000

  • GTVp + 7mm to 10mm margin up to skin surface
  • Bilateral inguinal lymph node regions

PTV_5750

  • GTVn + 5 mm margin
  • Crop from skin (if uninvolved) and bowel

PTV_6600 (sequential boost)

  • GTVp + 5-7 mm margin (margin dependent on tumor size, daily image guidance and setup reproducibility)
  • Crop out uninvolved rectum

 

Dose:

  • 50 Gy in 25 fractions simultaneous integrated boost to gross primary tumor (include elective bilateral inguinal nodal regions if inguinal nodes are positive).
  • 55-60 Gy in 25 fractions simultaneous integrated boost to gross inguinal and pelvic nodes.
    • Bulky nodes (>3cm) may require higher dose; aim for highest achievable while respecting bowel constraints and patient tolerance.
  • Sequential boost of 14-16 Gy in 7-8 fractions to primary tumor and bulky inguinal nodes (if present) to reach cumulative dose 64-66 Gy (EQD2).
  • For post-operative: consider 45-50 Gy to primary surgical bed with negative margins and 54-60 Gy for close or positive margins.
    • Inguinal LN to 45-50 Gy in uninvolved, 50-55 Gy if involved, and up to 54-64 Gy to LNs with extracapsular extension on pathology.

  • Ensure adequate inguinal CTV margin around inguinal vessels per previously published data (Kim et al PRO 2012).
  • Treatment of pelvic nodes should be considered even in absence of clinically/radiographically positive inguinal nodes if large primary tumor and invasion of neighboring organs.
  • If pelvic LN+, consider treating entire common iliac LN chain.
  • Assess skin toxicity weekly on OTV, skin care is extremely important and treatment break may be necessary depending on patient tolerance.
  • Contour rectum to extend to perineum, cropped out of CTV if uninvolved. 
  • Small bowel should be contoured at least 2 cm cephalad to PTV and include all bowel loops and any place within the peritoneal cavity that small bowel could lie.
  • For patients with an intact cervix/vagina - locally advanced will include the whole vagina +/- uterus.
  • Option to perform boost sequentially is beneficial because of the ability to switch to boost and allow vulvar skin to heal.

Constraints:

  • Small Bowel
    • V40 Gy < 30%
    • Dmax < 51 Gy
  • Rectum
    • V40 Gy < 80%
    • Dmax < 65 Gy
  • Bladder
    • V45 Gy < 50%
    • Dmax < 65 Gy
  • Femoral Heads
    • V45 Gy < 50%
    • Dmax < 55 Gy
  • Body – PTV
    • V110% <  1 cc (i.e., keep hotspot that is outside PTV under 110%)