eContour

43 year old female with post-coital bleeding and subsequent abnormal pap smear found to have FIGO Stage IIA (AJCC Stage cT2aN0M0) p16+ endocervical adenocarcinoma of the cervix (3.6x2.3x4.2cm) receivingto definitive chemoradiation followed by brachytherapy boost

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Technique:

  • She was treated initially with 45Gy in 25fx with concurrent weekly cisplatin 40mg/m2
  • Patient had excellent response to initial chemoradiation with residual tumor in the anterior cervix
  • A Smit sleeve was placed, and the patient had a 5cm tandem and 3cm ovoids placed in clinic for each fraction with packing anteriorly and posteriorly to displace the bladder and rectum. MRI was obtained with the first fraction with applicator in place.  
  • Brachytherapy was started after completion of EBRT and chemo to complete all treatment within 8 weeks

Dose:

  • She received brachytherapy boost 28Gy in 4fx to HR-CTV, treated twice weekly

Simulation:

  • Place Foley with contrast
  • Speculum exam to visualize cervix and place applicator
  • Pack bladder anteriorly and rectum posteriorly with gauze or balloons

During sim:

  • Confirm tandem/smit sleeve is in proper location in uterus
  • Confirm proper alignment of ovoids with tandem and sleeve
  • Confirm no perforation of uterus/cervix
  • Confirm packing is not displacing ovoids from cervix
  • Confirm adequate packing of bladder and rectum
  • Confirm no extensive gas within rectum, consider using red tube catheter to release gas from rectum

  • OARs were adjusted based on MRI as MRI obtained after CT sim
  • GTV included gross tumor at the time of brachytherapy, determined by imaging and examination
  • HR-CTV included gross tumor, the entire cervix, and regions of indeterminate T2-weighted signal (i.e. gray zones) as seen on MRI at time of brachytherapy.
  • IR-CTV is optional and is the HR-CTV with an asymmetrical expansion*, not extending into OARs, and including sites of initial disease involvement
  • The IR-CTV expansion is 0.5-1.0cm globally with an additional 0.5cm superiorly into the uterus, inferiorly into the vagina, and laterally in bilateral para-cervical tissues
  • General length of cervix is about 3cm

 

  • Largest tolerated ovoids used to reduce relative vaginal surface dose due to inverse square law
  • Target goal and constraints per ASTRO Clinical Practice Guidelines
  • There are other common brachytherapy regimens given in combination with 4500cGy EBRT listed in ASTRO and ABS guidelines
  • HR-CTV D90 ≥ 80 Gy, with consideration of escalation for advanced disease or poor response to initial therapy
  • Rectum D2cc < 65-75 Gy 
  • Bladder D2cc < 80-90 Gy
  • Sigmoid D2cc < 70-75 Gy
  • Bowel D2cc < 70-75 Gy