3 Results
3.1 Post-implant dosimetry
The mean
±
standard deviation of post-implant D90 (the doses
delivered to 90% of the target volume) of the patients was 115.1 ± 19.9
Gy, and higher than the prescribed dose for each patient. The
V100 (the percentage of target volume that receives at
least 100% of the prescribed dose) was more than 85% for every patient
with a median of 94.5% ranging from 87.7 to 96.1, and the mean ±
standard deviation of V150 (the percentage of target
volume that receives at least 150% of the prescribed dose) was 50.2%
±
11.7%.
3.2 Local control
During the follow-up, the local
control rate was 7/7. No recurrent lesion was found in the patients
undergoing surgery combined with brachytherapy. In patients treated with
sole brachytherapy, 4/5 were radiological partial response and 1/5 was
radiological complete response. In those reaching radiological partial
response, 3/4 were pathological complete response. Among all 5 patients
undergoing sole brachytherapy, local control condition was also
described as the changes of tumor maximum diameter, MR signal evaluation
and pathological examination by core-needle aspiration as follow.
3.2.1 Tumor maximum diameter
There was only one lesion in every patient. And the tumor maximum
diameter at first visit, 2 months’ follow-up, 6 months’ follow-up and
last follow-up were demonstrated in Figure 2. All the lesions were
stable at the first follow-up, and reached partial regression or
complete regression at 6 months’ follow-up (Figure 3).
3.2.2 MR signal evaluation
Of the patients treated with sole brachytherapy, 3/5 underwent MR
examination before and after the brachytherapy. The MR were performed no
more than 1 month before the pre-operative or post-operative biopsy. All
lesions presented hyper-intense compared with muscle in the
pre-operative T2 weighted images, and 2 lesions turned to hypo-intense
and 1 lesion turned to isointense compared with muscle in the
post-operative T2 weighted images (Figure 4).
3.2.3 Core-needle aspiration
Pathological examination by core-needle aspiration was performed on 3/4
of the lesion reaching partial regression, and specimens from at least
five spots in the radiological tumor volume were taken under the
guidance of the far-infrared navigation guidance system mentioned
before. No tumor cell was found in all the specimens (Figure 5). Thus,
all the patients receiving core-needle aspiration were regarded as
pathological complete regression.
3.3 Side effects or toxicity
No operative complication such as cerebrospinal fluid leakage, hematoma
or infection was observed. Radiation related acute toxicity, including
dry desquamation, edema and erythema on skin were observed in all the
patients, while 6/7 were classified as RTOG grade 1 and 1/7 was
classified as RTOG grade 2, and no RTOG grade 3 or 4 toxicity were
observed. None experienced late toxicity. Notably, no radiation related
growth retardation and secondary cancer were observed.