Tuesday, March 31, 2009
Friday, March 27, 2009
The standard of care for oligometastases is consideration of surgery if feasible - Patchell study demonstrating survival advantage to surgery in addition to WBRT.
Plenty of data on SRS and WBRT combinations, none compare directly to surgery. SRS doses are defined by RTOG 9005. <20mm 24Gy, 20-30mm 18Gy, 30-40mm 15Gy.
Conformality Index is volume encompassed by the prescription isodose line divided by the volume of the PTV. Goal of Rx is to be less than 2, though this can be impossible for very small lesions, and a CI of 3-4 would be acceptable.
GTV to PTV expansions are 1mm as per Baumert BG, Int J Radiat Oncol Biol Phys. 2006 Sep 1;66(1):187-94 - pathologic study of 45 pts, 76 mets. demonstrating that for most histologies microscopic extension was <1mm, except for melanoma and SCLC which were greater.
Process at Duke is to use a non-invasive frame for immobilization. With this scans can be performed prior to SRS delivery and the patient does not have to wait all day in the department with a head frame on. The exceptions are for very small targets near critical structures - trigeminal neuralgia patients and acoustic neuromas for example. In these cases we will still use an invasive frame.
Thin cut SRS protocol MRI with contrast is obtained and fused with the planning image. Often for small convex tumors, 4-5 dynamic conformal arcs offer a simple solution. Remember that the MLC shapes must include a dosimetric margin. For larger concave targets, such as AVMs, IMRS (intensity modulated radiosurgery) may be utilized for better conformality and for sparing normal brain.
With this approach, patients can come in at a scheduled treatment time, and complete treatment in a few hours.
All plans are reviewed with a Neurosurgeon, and if there is concern about proximity to the motor strip, we will ofter back off the dose. For the lesion presented, measuring 1.4cm, we backed the dose off to 20Gy.
Limit on the brainstem is a conservative 12Gy in a single fraction, and for optic apparatus our limit is 8Gy.
Quick rundown of SRS doses:
Mets <2cm 24Gy
Mets 2-3cm 18Gy
Mets 3-4cm 15Gy
Acoustic Neuroma 12.5Gy (54Gy fractionated)
Meningioma 15-16Gy (50.4Gy fractionated benign, 54-60Gy fractionated malignant)
AVM 20 Gy marginal dose (keep V12 less than 26cc for most sites, refer to this Flickinger paper)
Thursday, March 26, 2009
Journal Club - MRC CR07 lancet 2009
presents a pt with moderately differentiated invasive adeno carcinoma. uT3 by EUS, one 8mm LN. 8cm from verge. What is the ideal sequence of treatment.
Reviewed the Swedish rectal trial. 1187 pt with resectable rectal cancer, randomized to 5Gy x 5 preop vs surgery alone. Improvement in LR, CSS, and OS. Update JCO 2005; 23:5644, looking at R0 surgical subset, all endpoints are maintained. However, no TME was used.
Dutch Rectal trial. All undergoing TME 1861 patients. Randomized to preop 5Gy x 5 vs surgery alone. NEJM 2001;345:368. LR at 6yrs 11% vs 6% p<0.001.
Preop vs Postop: German trial NEJM 2004;351:1731. Preop 50.4Gy with 5FU, vs Postop 55.8Gy with 5FU. LR 13 vs 6% SS. 90% compliance to CT or RT in the preop group, 50% compliance in the postop group.
Are we overtreating some patients. Probably – This MRC trial is aimed at determining this.
1350pts randomize to surgery first with CTRT to follow if margins <=1mm, vs. Preop RT 5Gy x 5. 92% of surgeries were with TME technique. 40% in preop group got chemotherapy, 45% in the postop group got chemotherapy.
Primary endpoint LR, secondary – OS, DFS, toxicities, etc.
Started as a non-inferiority trial, but changed to a superiority trial for 5Gy x 5. 2.5% improvement in LR at 5 years. Margins was 10 vs 12% (NS).
LR HR 0.39 p<0.001. p="0.013." p="0.4).">
Pathologic Assessment (Quirke Lancet 2009). Looked at true TME plane vs intramesorectal vs intra muscularis propria: 3yLR 13% vs 7% vs 4% p=0.0039. In the optimal group: True TME + preoperative RT resulted in 3yr LR of 1%.
So with the staging that was performed, we cannot select patients who do not need RT.
Thursday, March 19, 2009
- Loss of resistance during instrumentation
- Extension into the uterus for greater than expected distance
- Severe caginal bleeding
- Perioperative Hypotension
- Signs of infection
Friday, March 13, 2009
Friday, March 6, 2009
The Lancet has two articles today reporting the results of the MRC CR07 and NCIC-CTG C016 trials.
The first reports the primary results of the trial:
1350 patients with operable adenocarcinoma of the rectum randomized to
1. 25 Gy in five fractions preop versus2. Selective postoperative chemoradiotherapy (45 Gy in 25 fractions with concurrent 5-fluorouracil) for positive radial marginsMedian follow-up = 4 years.
61% reduction in the relative risk of local recurrence for patients receiving preoperative radiotherapy (HR 0·39, 95% CI 0·27—0·58, p<0·0001)
3 year reduction in local recurrence was of 6·2% (95% CI 5·3—7·1) (4·4% preoperative radiotherapy vs 10·6% selective postoperative chemoradiotherapy)
Disease-free survival improvement of 24% for patients receiving preoperative radiotherapy (HR 0·76, 95% CI 0·62—0·94, p=0·013
3 years DFS difference of 6·0% (95% CI 5·3—6·8) (77·5% vs 71·5%)
Overall survival did no different (HR 0·91, 95% CI 0·73—1·13, p=0·40)
Thus this suggests that at least currently we are unable to select out patients that might be spared RT.
The Second is from pathologist Phil Quirke who reports on the surgical quality and it's affect on local recurrence.
1156 patient tumors underwent rigorous pathologic examination:
128 (11%) had + margin
the mesorectal plane was achieved in 604 (52%)
intramesorectal plane in 398 (34%)
muscularis propria plane in 154 (13%)
Negative Margin vs Positive margin: LR Hazard ratio (HR) was 0·32 (95% CI 0·16—0·63, p=0·0011), 3yr LR 6% (5—8%) and 17% (10—26%) respectively
TME LR HR was 0·32 (0·16—0·64), intramesorectal plane LR HR was 0·48 (0·25—0·93). 3yr LR was 4% (3—6%) for TME, 7% (5—11%) for intramesorectal, and 13% (8—21%) for muscularis propria groups.
All subgroups benefited from preop RT.
good TME + preop RT resulted in 3yr LR of 1%Thus good surgery + preop RT results in the best LR rates in this disease.