eContour

86 y/o F with squamous cell carcinoma of the right labia majora, cT2bN2bM0, Stage IIIB, with involvement of the distal urethra and bilateral inguinal lymph nodes.

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Technique: She recieved definitive concurrent chemoradiation.

  • Given distal urethral involvement and concern for potential positive margins with upfront resection, definitive radiation therapy with concurrent chemotherapy was recommended per Beriwal Gynecol Oncol 2008 and Beriwal IJROBP 2013.
  • Intensity modulated radiation therapy (IMRT) was used with daily cone beam CT.
  • Monitor for vulvar swelling during treatment on daily CBCT as vulva can swell outside of target volume.

Dose:

  • The following was treated in a simultaneous integrated boost fashion in 25 fx per Richman Gynecol Oncol 2020:
    • Pelvic lymph nodes (common, internal, external, and obturator nodes): 4500 cGy in 25 fx.
    • Entire vulva:  4500 cGy in 25 fx.
    • Bilateral Inguinal node basin: 5000 cGy in 25 fx.
    • Primary vulvar tumor: 5000 cGy in 25 fx.
    • Involved inguinal nodes: 5750 cGy to 6000 cGy in 25 fx.
  • Following this, a sequential boost to the primary tumor was given of 1600 cGy in 8 fx, totaling 6600 cGy in 33 fx to the primary vulvar tumor.

Simulation:

  • Simulate with full bladder and empty rectum with oral contrast.
  • Ensure patient is in frog leg position to allow sparing of the skin in the upper inner thigh.
  • Consider wiring the primary tumor.

 

Case contributed by Allegheny Health Network Cancer Institute.

Contours and treatment techniques per Gaffney IJROBP 2016 and Rao Adv Radiat Oncol 2017.

  • GTV_6000 gross inguinal nodes = gross inguinal nodes
  • PTV_6000 gross inguinal nodes = GTV_6000 + 0.5 cm
  • CTV_5000 inguinals = bilateral inguinal nodal basins
  • PTV_5000 inguinals = CTV_5000 inguinals + 0.7 cm
  • GTV_5000 primary = primary vulvar tumor
  • CTV_5000 primary = GTV_5000 primary + 0.7 cm, anatomically trimmed to confined to vulva
  • PTV_5000 primary = CTV_5000 primary + 0.7 cm
  • CTV_4500 vulva = entire vulva
  • PTV_4500 vulva = CTV_4500 vulva + 0.7 cm, except 1.0 cm inferior
  • CTV_4500 pelvis = vessels and perinodal tissue of internal, external iliac, obturator, and common iliac nodes
  • PTV_4500 pelvis = CTV_4500 pelvis + 0.7 cm
  • Sequential Boost (1600 cGy in 200 cGy/fx):
    • GTV_1600 primary= primary vulvar tumor
    • CTV_1600 primary= GTV_1600 primary + 5 to 7 mm margin, anatomically trimmed to confined to vulva
    • PTV_1600 primary= CTV_1600 primary + 5 to 7 mm margin, except 1.0 cm inferior

 

  • If the GTV extends beyond the vulva:
    • CTV= GTV + 1 cm margin
  • If the primary vulvar lesion involves the vagina (ie, tumor proximal to the hymenal ring):
    • CTV= GTV + 3 cm margin. If uncertainty in vaginal extent, include full extent of vagina.
  • If the primary vulvar lesion is periurethral (ie, involving the urethral meatus):
    • CTV = GTV + at least 2 cm of urethra.
    • If disease extends into the mid or proximal urethra, the entire urethra and bladder neck should be included in the CTV.
  • If the primary lesion is anus, anal canal, bladder or rectum:
    • CTV= GTV + 2 cm of anorectum or bladder
  • Nodal groups to be included in all cases:
    • Common iliac
    • External iliac
    • Internal iliac
    • Obturator
    • Inguinal
  • Additional nodal groups to be included if tumor involves proximal vagina:
    • Include presacral nodes down to S3
  • Additional nodal groups to be included if tumor involves anus or anal canal:
    • Include presacral nodes down to S3
    • Mesorectal nodes

 

  • Bolus:
    • Scanning at the time of simulation with bolus both on and off.
    • Alternatively, virtual bolus can also be added and used to guide actual bolus as needed.
  • Monitor closely for tumor shrinkage, vulvar edema, or other developments (eg, lymphocyst formation) during treatment, as this could warrant replanning.
  • Consider placement of a dosimeter on the vulva at the first fraction to ensure adequate skin dosing.