Thursday, March 19, 2009

Brachytherapy for Cervical Cancer

AC presents on complications of brachytherapy for cervical cancer.

Reviews the treatement of a IIIB cervical cancer (invovlement of the sidewall).

Treat to 45Gy with 1.8 Gy/day and 40mg/m2 CDDP weekly.  Follow by a T&O boost to an additional 40 Gy to point A.  Sidewall boost to an additional 5-10Gy (with a goal of 60-65Gy to point B).  

For dosimetry, patients regularly undergo CT after implant.  Occaisionally one can see a perforation of the superior aspect of the uterus.  The Uterus usually sounds to around 8cm maximum, and one usually will set the flange to just below the sound.  

DPB makes the point that often perfs are created during the sounding process, and emphasises that the sound should be held lightly with 2 fingers and the thumb to reduce the risk of perforation.

Risks: Hemmorhage, Infection, and Irradiation of adjacent structures.

Clinically Detecting a Perforation: 
  • Loss of resistance during instrumentation
  • Extension into the uterus for greater than expected distance
  • Severe caginal bleeding
  • Perioperative Hypotension
  • Signs of infection
Detection on plain films can be challenging due to indivdual variation in anatomy.

U/S may be used per Fox Chase - with a full bladder a transabdominal u/s may be used throughout the placement of the tandem.

Granai Ob Gyn 1990 75(1):110.  50 placements.  10% frank perforation per u/s, 24% with myometrial penetration, and 34% with suboptimal positioning of the tandem.  U/S affected management in 21/50 placements.  In follow up 73 placements were performed with real-time U/S guidance, and only 1 was suboptimally placed.

Barnes Int J Gyn Cancer 2007;17:821.  CT detection series.  124 LDR insertions - compared Rad Oncs clinical impression with CT findings.  14% had perfed by CT.  MD concern sensitivity 53%, specificity 84%.  MD concern, >=60yo, tumor size.

Irvin 2003; Gyn Onc 90:113.  Laparoscopic series from UVA to ensure correct tandem placement.  

Kim 1983; Radiology 147:249.  622 pt 1971-1981, UAB.  14 perforations, managed by halting the application, and close monitoring.  1 had pelvic abscess, 1 had pyometria.  Only 7 were given prophylactic antibiotics, and none of these had complications.

Jhingran & Eifel.  2000;IJROBP 46(5):1177.  4043 pt undergoing LDR.  113 (3%) had perforation, in 50% tandem was repositioned and treatment proceeded, 41% had the tandem removed and successfully reinserted later.  9% were unable to undergo brachytherapy.  Demonstrated that there were increased risks with older age.   Thromboembolisms seen in 0.3% (11pts).  

What about HDR - 169pt from Wisconsin, Petereit 1998;IJROBP 42(5):1025. 822 placements.  19 perforations seen by US (2% of insertions, 11% of patients). Routine antibiotic prophylaxis was not used.  Age and PS were associated with complications

In Summary: Perforation occurs in 2-4% of insertions, with an increase of up to 10-15% with prospecitive imaging surveillance.  Age >60 is a risk factor.  Conservative repositioning may be performed without clinically relavent complications.  For limited fundal perforations, based on experience from Dr. Montana at Duke, the tandem may be loaded with a spacer at the superiormost location without repositioning, provided that dosimetry is accpetable.


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