A biologically adapted dose-escalation approach, demonstrated for 18F-FET-PET in brain tumors

PURPOSE

To demonstrate the feasibility of a biologically adapted dose-escalation approach to brain tumors.

MATERIAL AND METHODS

Due to the specific accumulation of fluoroethyltyrosine (FET) in brain tumors, (18)F-FET-PET imaging is used to derive a voxel-by-voxel dose distribution. Although the kinetics of (18)F-FET are not completely understood, the authors regard regions with high tracer uptake as vital and aggressive tumor and use a linear dose-escalation function between SUV (standard uptake value) 3 and SUV 5. The resulting dose distribution is then planned using the inverse Monte Carlo treatment- planning system IKO. In a theoretical study, the dose range is clinically adapted from 1.8 Gy to 2.68 Gy per fraction (with a total of 30 fractions). In a second study, the maximum dose of the model is increased step by step from 2.5 Gy to 3.4 Gy to investigate whether a significant dose escalation to tracer-accumulating subvolumes is possible without affecting the shell-shaped organ at risk (OAR). For all dose-escalation levels the dose difference Delta D of each voxel inside the target volume is calculated and the mean dose difference Delta D and their standard deviation sigma Delta D are determined. The dose to the OAR is evaluated by the dose values D OAR 50% and D OAR 5%, which are the dose values not exceeded by 50% and 5% of the volume, respectively.

RESULTS

The inhomogeneous dose prescription is achieved with high accuracy (Delta D < 0.03 +/- 0.3 Gy/fraction). The maximum dose can be increased remarkably, without increasing the dose to the OAR (standard deviation of D OAR 50% < 0.02 Gy/fraction and of D OAR 5% < 0.05 Gy/fraction).

CONCLUSION

Assuming that regions with high tracer uptake can be interpreted as target for radiotherapy, (18)F-FET-PET-based "dose painting by numbers" applied to brain tumors is a feasible approach. The dose, and therefore potentially the chance of tumor control, can be enhanced. The proposed model can easily be transferred to other tracers and tumor entities.

Influence of calculation algorithm on dose distribution in irradiation of non-small cell lung cancer (NSCLC) collapsed cone versus pencil beam

PURPOSE

. The influence of two different calculation algorithms ("pencil beam" [PB] versus "collapsed cone" [CC]) on dose distribution, as well as the dose-volume histograms (DVHs) of the planning target volume (PTV) and the organs at risk was analyzed for irradiation of lung cancer.

MATERIAL AND METHODS

. Between 10/2001 and 02/2002 three-dimensional treatment planning was done in ten patients with lung cancer (Helax, TMS((R)), V.6.01). The PTV, the ipsilateral lung (IL) and the contralateral lung (CL) were defined in each axial CT slice (slice thickness 1 cm). Dose distributions for three-dimensional multiple-field technique were calculated using a PB and a CC algorithm, respectively. Normalization was in accordance with ICRU 50. The DVHs were analyzed relating the minimum, maximum, median and mean dose to the volumes of interest (VOI).

RESULTS

. Median PTV amounted to 774 cm(3). Minimum dose within the PTV was 67.4% for CC and 75.6% for PB algorithm (p = 0.04). Using the CC algorithm, only 76.5% of the PTV was included by the 95% isodose, whereas 90.1% was included when the PB algorithm (p = 0.01) was used. Median volume of IL amounted to 1 953 cm(3). Mean dose to IL was 43.0% for CC and 44.0% for PB algorithm (p = 0.02). Median volume of IL within the 80% isodose was 19.6% for CC and 24.1% for PB algorithm (p < 0.01). Median volume of CL amounted to 1 847 cm(3). Mean dose to CL was 17.4% for CC and 18.1% for PB algorithm (p < 0.01). Volume of CL within the 80% isodose was 3.3% for CC and 4.1% for PB algorithm (p = 0.03).

CONCLUSION

. The CC and PB calculation algorithms result in different dose distributions in case of lung tumors. Particularly the minimum dose to the PTV, which may be relevant for tumor control, is significantly lower for CC. Since it is generally accepted that the CC algorithm describes secondary particle transport more exactly than PB models, the use of the latter should be critically evaluated in the treatment planning of lung cancer.

Influence of rectum delineation (rectal volume vs. rectal wall) on IMRT treatment planning of the prostate

PURPOSE

To evaluate the delineation of either the rectal volume (RV) or the rectal wall (RW) in intensity-modulated radiotherapy (IMRT) for prostate cancer: influence on dose distribution to the targets and organs at risk (OARs) was investigated.

MATERIAL AND METHODS

For ten patients with localized prostate cancer IMRT treatment plans were generated with the RV, wall including the filling, and the RW without the lumen as OAR (plan-RV and plan-RW), respectively. Two different IMRT treatment- planning systems (TPS) were utilized. The influence on target coverage and sparing of OARs was investigated.

RESULTS

No influence was seen on target coverage and sparing of the bladder and femoral heads. Doses to the RV were significantly reduced in plan-RV for all evaluated dose levels: maximum 26% and 17%, respectively, in both TPS. The dose distribution to the RW was not significantly different between plan-RV and plan-RW.

CONCLUSION

The different delineation of the OAR rectum significantly affected the inverse IMRT treatment-planning process. The use of the RV as OAR resulted in improved dose distributions to the RV. Therefore, it is suggested using the RV as OAR in IMRT treatment planning of the prostate.

Comparison of direct machine parameter optimization versus fluence optimization with sequential sequencing in IMRT of hypopharyngeal carcinoma

Background

To evaluate the effects of direct machine parameter optimization in the treatment planning of intensity-modulated radiation therapy (IMRT) for hypopharyngeal cancer as compared to subsequent leaf sequencing in Oncentra Masterplan v1.5.

Methods

For 10 hypopharyngeal cancer patients IMRT plans were generated in Oncentra Masterplan v1.5 (Nucletron BV, Veenendal, the Netherlands) for a Siemens Primus linear accelerator.

For optimization the dose volume objectives (DVO) for the planning target volume (PTV) were set to 53 Gy minimum dose and 59 Gy maximum dose, in order to reach a dose of 56 Gy to the average of the PTV. For the parotids a median dose of 22 Gy was allowed and for the spinal cord a maximum dose of 35 Gy. The maximum DVO to the external contour of the patient was set to 59 Gy. The treatment plans were optimized with the direct machine parameter optimization ("Direct Step & Shoot", DSS, Raysearch Laboratories, Sweden) newly implemented in Masterplan v1.5 and the fluence modulation technique ("Intensity Modulation", IM) which was available in previous versions of Masterplan already. The two techniques were compared with regard to compliance to the DVO, plan quality, and number of monitor units (MU) required per fraction dose.

Results

The plans optimized with the DSS technique met the DVO for the PTV significantly better than the plans optimized with IM (p = 0.007 for the min DVO and p < 0.0005 for the max DVO). No significant difference could be observed for compliance to the DVO for the organs at risk (OAR) (p > 0.05). Plan quality, target coverage and dose homogeneity inside the PTV were superior for the plans optimized with DSS for similar dose to the spinal cord and lower dose to the normal tissue. The mean dose to the parotids was lower for the plans optimized with IM. Treatment plan efficiency was higher for the DSS plans with (901 ± 160) MU compared to (1151 ± 157) MU for IM (p-value < 0.05).

Renormalization of the IM plans to the mean of the dose to 95% of the PTV (D₉₅) of the DSS plans, resulted in similar target coverage and dose to the parotids for both strategies, at the cost of a significantly higher dose to the normal tissue and maximum dose to the target. The relative volume of the PTV receiving 107% or more of the prescription dose V₁₀₇ increased to 35.5% ± 20.0% for the IM plan as compared to a mean of 0.9% ± 0.9% for the DSS plan.

Conclusion

The direct machine parameter optimization is a major improvement compared to the fluence modulation with subsequent leaf sequencing in Oncentra Masterplan v1.5. The resulting dose distribution complies better with the DVO and better plan quality is achieved for identical specification of DVO. An additional asset is the reduced number of MU as compared to IM.

Cetuximab, capecitabine, and oxaliplatin (Cet-CapOx) with concurrent radiotherapy (RT) in advanced rectal cancer (RC): Results of a phase I/II trial

4042

Background: CapOx given concurrently with neoadjuvant RT in rectal cancer is well tolerated and has achieved high rates of pathologic complete response (pCR) in phase II trials. Cetuximab is active in metastatic colorectal cancer. Synergy of cetuximab with RT resulted in improved survival (vs. RT alone) in head and neck cancer. This trial was to evaluate feasibility and efficacy of Cet-CapOx in RT of rectal cancer, with maximal tolerated dose as primary endpoint in phase I, and pCR as primary endpoint in phase II. Method: Patients (pts) had to have untreated, T3–4 and/or N+ disease per MRI or CT plus endoscopic ultrasound, M1 allowed, normal organ function. During conventionally fractionated RT (1.8 Gy for 28 days [d]), cetuximab was given in standard dose (400 mg/m2 on d - 7, then 6 weekly doses of 250 mg/m2, to d35). CapOx was administered as in the phase II trial of our group (Rödel et al, J Clin Oncol 2007), with oxaliplatin (50 mg/m2 d 1,8,22 and 29) plus capecitabine (d1–14 and d22–35) at 3 dose levels: 1,000, 1,300 and 1,650 mg/m2/day. Results: 60 pts were enrolled: Median age 62 [35–83] yrs., male 61%, T3/T4 83/17%, N+ 85%, M1 20%. 7/ 3/ 50 pts. were treated on levels 1/ 2/ 3: as only 1 pt. experienced DLT (diarrhea 4°) on level 1 and none on level 2, level 3 was chosen for phase II (n=50 pts.). Most common toxicity was CTC grade 3 diarrhea in 14% of pts. Full dose of all drugs and of RT was administered in >90% of cycles. No grade 4 toxicity occurred. 53/60 pts underwent resection after completed chemoradiation without increase of perioperative complications when compared to historic controls of CapOx-RT alone. Radiologic downstaging (17 pts. evaluated so far) was seen in 35% for T category and in 67% for N category. Pathologic complete response (45 pts. evaluable) was observed in 9% of pts, another 38% had “good regression” (>50% of tumor cells). Conclusion: CapOx can safely be combined with cetuximab without requiring dose reduction of chemo- or radiotherapy and leads to significant downstaging. However, the relatively low rate of pathologic responses underachieved the assumptions.

[Table: see text]

Split course hyperfractionated accelerated radio-chemotherapy (SCHARC) for patients with advanced head and neck cancer: influence of protocol deviations and hemoglobin on overall survival, a retrospective analysis

Background

The advantage of hyperfractionated accelerated radiation therapy for advanced head and neck cancer has been reported. Furthermore, randomized trials and meta-analyses have confirmed the survival benefit of additional chemotherapy to radiotherapy. We retrospectively analyzed the efficiency and toxicity of the Regensburg standard therapy protocol "SCHARC" and the overall survival of our patients.

Methods

From 1997 to 2004, 64 patients suffering from advanced head and neck cancer (88 % stage IV, 12 % stage III) were assigned to receive the SCHARC protocol. Around half of the patients were diagnosed with oro-hypopharynx carcinoma (52 %), one third with tongue and floor of mouth tumors (29 %) and one fifth (19 %) suffered from H & N cancer at other sites. The schedule consisted of one therapy block with 30 Gy in 20 fractions over a two week period with concomitant chemotherapy (d 1–5: 20 mg/m²/d DDP + 750–1000 mg/m²/d 5FU (cont. infusion). This therapy block was repeated after a fortnight break up to a cumulative dose of 60 Gy and followed by a boost up to 70 Gy (69–70.5 Gy). All patients assigned to this scheme were included in the survival evaluation.

Results

Forty patients (63 %) received both radiation and chemotherapy according to the protocol. The mean follow up was 2.3 years (829 d) and the median follow up was 1.9 years (678 d), respectively. The analysis of survival revealed an estimated 3 year overall survival rate of 57 %. No patient died of complications, 52 patients (80 %) had acute grade 2–3 mucositis, and 33 patients (58 %) suffered from acute grade 3 skin toxicity. Leucopenia was no major problem (mean nadir 3.4 g/nl, no patient < 1.0 g/nl) and the mean hemoglobin value decreased from 13.2 to 10.5 g/dl. Univariate analysis of survival showed a better outcome for patients with a hemoglobin nadir >10.5 g/dl and for patients who completed the protocol.

Conclusion

The SCHARC protocol was effective in patients diagnosed with advanced head and neck cancer. It led to long-term disease control and survival in about 50 % of the patients with significant but acceptable toxicity. Most patients were not anemic at beginning of therapy. Therefore, we could assess the influence of pre-treatment hemoglobin on survival. However, a low hemoglobin nadir was associated with poor outcome. This result suggests an influence of anemia during therapy on prognosis.

Enhanced radiation sensitivity and radiation recall dermatitis (RRD) after hypericin therapy -- case report and review of literature

BACKGROUND

Modern radiotherapy (RT) reduces the side effects at organ at risk. However, skin toxicity is still a major problem in many entities, especially head and neck cancer. Some substances like chemotherapy provide a risk of increased side effects or can induce a "recall phenomenon" imitating acute RT-reactions months after RT. Moreover, some phototoxic drugs seem to enhance side effects of radiotherapy while others do not. We report a case of "radiation recall dermatitis" (RRD) one year after RT as a result of taking hypericin (St. John's wort).

CASE REPORT

A 65 year old man with completely resected squamous cell carcinoma of the epiglottis received an adjuvant locoregional RT up to a dose of 64.8 Gy. The patient took hypericin during and months after RT without informing the physician. During radiotherapy the patient developed unusual intensive skin reactions. Five months after RT the skin was completely bland at the first follow up. However, half a year later the patient presented erythema, but only within the area of previously irradiated skin. After local application of a steroid cream the symptoms diminished but returned after the end of steroid therapy. The anamnesis disclosed that the patient took hypericin because of depressive mood. We recommended to discontinue hypericin and the symptoms disappeared afterward.

CONCLUSION

Several drugs are able to enhance skin toxicity of RT. Furthermore, the effect of RRD is well known especially for chemotherapy agents such as taxans. However, the underlying mechanisms are not known in detail so far. Moreover, it is unknown whether photosensitising drugs can also be considered to increase radiation sensitivity and whether a recall phenomenon is possible. The first report of a hypericin induced RRD and review of the literature are presented. In clinical practise many interactions between drugs and radiotherapy were not noticed and if registered not published. We recommend to ask especially for complementary or alternative drugs because patients tend to conceal such medication as harmless.

Randomized phase II trial comparing gemcitabine/cisplatin-based chemoradiotherapy (CRT) to 5-FU-based CRT in patients with locally advanced pancreatic cancer

4038

Background: CRT is a relevant treatment option for patients with unresectable pancreatic cancer. Up to now, 5-FU has been the drug of choice for concurrent CRT. Based on evidence that also gemcitabine may improve the antitumor activity of radiation, a randomized phase II trial was undertaken. Methods: Patients with locally advanced, non-metastatic and histologically proven pancreatic cancer were included into a three-arm trial. In arm treatment arm A, radiation (CTV I up to 50.0 Gy, conventional fractionation) was applied concurrently with protracted venous infusion of 5-FU (350 mg/m2/irradiation day). In treatment arm B, patients received radiotherapy together with gemcitabine (300 mg/m2/d 30 minute infusion) and cisplatin (30 mg/m2/d 60 minute infusion) applied on days 1, 8, 22, and 29. In treatment arm C, patients received an identical regimen of CRT as described for arm B which was followed by 4 cycles of chemotherapy with gemcitabine (1000mg/m2, 30 min iv) plus cisplatin (50mg/m2) applied at 2-week intervals. Patients were stratified for Karnofsky performance status (KPS ≥80% vs. <80%). The primary end-point of the trial was the 9-months survival rate. Results: Ninety-six patients with a median age of 63.5 years (range 40–75 years) were included into the trial from 01/02 until 06/05 (arm A: 32 patients, arm B: 33 patients, arm C: 31 patients). Two patients did not complete CRT. At the time of evaluation, 66 patients (70.2%) had died. 9-months survival rate was 60%, 58%, and 46% in treatment arms A, B, and C, respectively. Median overall survival in arm A was 9.6 mo (95% CI, 8.7–10.5 mo), in arm B 9.6 mo (95%CI, 7.4–11.8 mo), and in arm C 6.1 mo (95% CI, 1.6–10 mo). Secondary end-points such as treatment-related toxicity, response rate, secondary resectability, and time to progression are under evaluation. Conclusions: CRT with gemcitabine plus cisplatin is not superior to 5-FU-based CRT with regard to the primary end-point of 9-months survival rate. Updated results will be presented at the meeting.

No significant financial relationships to disclose.

Clinical Results of Intracoronary Brachytherapy (ICBT) for Multiple In-Stent Restenosis

BACKGROUND AND PURPOSE

Treatment of in-stent restenosis (ISR) with percutaneous coronary intervention (PCI) alone is often followed by early re-restenosis. The present study focused on the effect of intracoronary brachytherapy (ICBT) on multiple in-stent restenosis (MISR) after repeated PCI.

PATIENTS AND METHODS

40 patients (27 male, 13 female, age: 66 +/- 9 years) with MISR (two to six ISRs, median three ISRs) were retrospectively analyzed. All patients were treated by using the Novoste((R)) Beta-Cathtrade mark 3.5F System after PCI. The target vessel received 18.4-25.3 Gy of radiation at a depth of 2 mm from the center of the source. The restenosis-free survival and overall survival were calculated by Kaplan-Meier analysis (log-rank). The time interval between last PCI without ICBT and the consecutive recurrence was compared with the follow-up time after PCI with ICBT.

RESULTS

The 3-year overall survival rate after ICBT was 93%. The 0.5-, 1-, 2-, and 3-year ISR-free survival rates after PCI + ICBT were 81%, 72%, 52%, and 38%, respectively. After PCI alone, the 0.5-, 1-, and 2-year ISR-free survival rates were 30%, 13%, and 0%, respectively. This difference was highly significant (p < 0.0001). Patients with more than three ISRs before ICBT had a better outcome (3-year ISR-free survival: 80%) than patients with only two or three ISRs before ICBT (3-year ISR-free survival: 25%; p < 0.05).

CONCLUSION

ICBT is highly effective and safe in patients with ISR. The results of this study are in accordance with the WRIST and BETA-WRIST data. After 6 months both studies revealed an ISR-free survival rate of 86% (WRIST) and 66% (BETA-WRIST), respectively. The ISR rates in the own control group (70%) were comparable to the placebo groups in WRIST (68%) and BETA-WRIST (72%). Interestingly, patients with more than three ISRs before ICBT had the lowest ISR rate after ICBT.

The Influence of Heterotopic Ossification on Functional Status of Hip Joint Following Total Hip Arthroplasty

PURPOSE

The functional failure induced by heterotopic ossification (HO) following total hip arthroplasty (THA) was analyzed and correlated to the radiologic failure.

PATIENTS AND METHODS

From July 1997 to July 2001, 315 patients (345 hips) received THA indicated by a hypertrophic osteoarthritis of higher degree (Kellgren grade III, IV). All patients were irradiated prophylactically for prevention of HO on the evening before surgery with a 7-Gy single fraction. The patients' median age was 66.3 years. Radiologic failure was assessed by comparison of pre- and postoperative hip X-rays (immediately and 6 months after surgery). Analysis of radiographs was performed according to the Brooker Score. Clinical failure was appraised by measurement of passive range of motion (ROM) of the hip joint with a standard goniometer. The t-test was used for statistical analysis.

RESULTS

281 patients (81.5%) did not develop HO. HO of Brooker grade I or II was found in 58 patients (16.8%). Six patients (1.7%) developed HO Brooker grade III or IV. There was a significant negative correlation between the degree of radiologic and clinical failure. ROM differed significantly between patients with HO Brooker grade 0, I, II and patients with HO Brooker grade III, IV. Comparing the pre- and postoperative ROM, all patients with Brooker grade 0, I and II showed a significant improvement of flexion, internal and external rotation, abduction and adduction movement. Patients with HO Brooker grade III and IV showed no improvement of ROM in the postoperative follow-up.

CONCLUSION

The development of HO following THA influences the physical function of the hip joint dependent on the degree of ossification. HO of lower degree (Brooker I, II) does not influence the clinical outcome, whereas HO of higher degree (Brooker III, IV) reduces the function of hip arthroplasty. Therefore, the purpose of a prophylactic therapy must be to reduce HO of higher degree.

Radiotherapy of prostate cancer with multileaf collimators (MLCs) optimization of the undulating dose distribution at the MLC edge

BACKGROUND AND PURPOSE

A technical modification for radiotherapy of prostate cancer is presented to smooth the scalloped dose pattern that occurs at treatment field edge, when a multileaf collimator (MLC) has been used.

MATERIAL AND METHODS

Ten patients with prostate cancer receiving postoperative, adjuvant irradiation were studied prospectively. By a three-dimensional planning system (TMS, Helax 6.1B) the irradiation was planned for an 18-MV linear accelerator (Primus 1, Siemens). The volumes of interest (VOI) were the planning target volume (PTV; the region of the prostate including the seminal vesicles), the volume of rectum (V(rectum)) and urinary bladder (V(bladder)). Two four-field techniques (0 degrees , 90 degrees , 180 degrees , 270 degrees ) were planned using "beam's eye view" for setting the leaf position of the MLC. For technique A the MLC was adapted to the PTV using a 0 degrees collimator angle for the lateral fields. For technique B the collimator angle of the lateral fields was optimized to compensate the cascade field shape. Dose-volume histograms of PTV, V(rectum) and V(bladder) were analyzed. The dose was prescribed for the reference point according to ICRU 50. Film dosimetry was used to show the dose pattern at the field edge produced by the two techniques.

RESULTS

Dose to PTV did not differ between technique A and B. Median dose to V(rectum) was 82.6% for technique A and 77.3% for technique B (p < 0.001). Technique A irradiates a larger V(rectum) than technique B being significant for all isodose levels tested. Median dose to V(bladder) did not differ for technique A and B (p > 0.05).

CONCLUSION

The presented technical modification is an effective method to blur the staggered dose distribution that results, when the MLC is conventionally stepped to adapt to the dorsal, irregular PTV border in irradiation of prostate. Especially for irradiation to escalated dose levels, this modification may reduce the dose to the rectum and thus the rectal side effects in comparison to the conventional MLC fields.

Preoperative irradiation for prevention of heterotopic ossification following prosthetic total hip replacement results of a prospective study in 462 hips

BACKGROUND

The effectiveness of pre- or postoperative radiotherapy for prevention of heterotopic ossification (HO) following total hip replacement (THR) has already been demonstrated in the past. Thereby, in most studies using preoperative radiotherapy patients were irradiated < 6 h before surgery. The purpose of this prospective study was to analyze the effectiveness of preoperative irradiation on the evening before surgery and to identify risk factors for HO in a homogeneous collective of patients.

PATIENTS AND METHODS

From July 1997 to July 2001, 416 patients (462 hips; 235 males, 227 females) received preoperative radiotherapy of the hip on the evening before surgery with a 7-Gy single fraction. The patients' median age was 67.1 years. The most frequent indication for radiotherapy was hypertrophic osteoarthritis (383 hips, 82.9%). Treatment results were assessed by comparison of pre- and postoperative hip X-rays (immediately and 6 months after surgery). The analysis of radiographs was performed according to the Brooker score.

RESULTS

The overall incidence of HO was 18.1% (n = 84), Brooker score 1 12.3% (n = 57), score 2 3.9% (n = 18), score 3 1.5% (n = 7), and score 4 0.4% (n = 2). Sex, body height, hypertrophic osteoarthritis of higher degree, size of the femoral component of the prosthesis, previous ipsi- or contralateral HO, and short course of nonsteroidal anti-inflammatory drug (diclofenac) therapy significantly influenced the HO rate in univariate analysis. In multivariate analysis, an interdependence of prosthesis size, sex and patient's height was found. From these three variables, only prosthesis size was statistically significant in multivariate analysis. The cumulative dose of diclofenac (< or = 300 mg or > 300 mg) within the first 7 postoperative days and previous ipsi- or contralateral HO influenced the incidence of HO in multivariate analysis.

CONCLUSION

Preoperative radiotherapy on the evening before surgery is an effective treatment modality to reduce overall (Brooker 1-4) and clinically relevant, severe HOs (Brooker 3-4), and includes several advantages compared to postoperative irradiation. Previous ipsi- and contralateral HOs were identified as high risk factors for HO in this study. In patients with these risk factors, the incidence of HO increased.

Association of anorectal dose–volume histograms and impaired fecal continence after 3D conformal radiotherapy for carcinoma of the prostate

PURPOSE

The late toxicity of fecal incontinence after pelvic radiotherapy is now frequently recognized but the etiology poorly understood. We therefore investigated associations between dose-volume histogram (DVH) parameters of the rectum and the anal canal with fecal continence as measured by an established 10-item questionnaire.

METHODS AND MATERIALS

Forty-four patients treated for carcinoma of the prostate with 58-72 Gy of 3D conformal radiotherapy between 1995 and 1999 who completed the questionnaire formed the study population. Total continence scores of treated patients obtained 1.5 years (median) after radiotherapy were compared to a control group of 30 patients before radiotherapy. Median, mean, minimum and maximum doses as well as the volume (% and ml) treated to 40, 50, 60 and 70 Gy were determined separately for anal canal and rectum. DVH parameters were correlated with total continence score (Spearman rank test) and patients grouped according to observed continence were compared regarding DVH values (Mann-Whitney U-test).

RESULTS

Median fecal continence scores were significantly worse in the irradiated than in the control group (31 vs. 35 of a maximum 36 points). In treated patients, 59%/27%/14% were classified as fully continent, slightly incontinent and severely incontinent. Continence was similar in the 58-to-62-Gy, 66-Gy and 68-to-72-Gy dose groups. No DVH parameter was significantly correlated with total continence score, but severely incontinent patients had a significantly higher minimum dose to the anal canal than fully continent/slightly incontinent, accompanied by portals extending significantly further inferiorly with respect to the ischial tuberosities.

CONCLUSIONS

Excluding the inferior part of the anal canal from the treated volume in 3D conformal therapy for carcinoma of the prostate appears to be a promising strategy to prevent radiation-induced fecal incontinence.

The relationship between belly board position and patient anatomy and its influence on dose-volume histogram of small bowel for postoperative radiotherapy of rectal cancer

The influence of three different belly board (BB) positions in radiotherapy of rectal cancer on the dose-volume histogram of the small bowel (SB) were analysed for 20 patients. Placing the lower border of the BB opening near the lumbosacral junction, both the volume of SB within the pelvis and the volume of SB within all tested dose levels were lower compared to its position near the symphysis or the lumbosacral junction.

Radiation-induced suppression of the Bmp2 signal transduction pathway in the pluripotent mesenchymal cell line C2C12: an in vitro model for prevention of heterotopic ossification by radiotherapy

Heterotopic ossification is a common complication after total hip replacement. Clinical studies showed the effectiveness of radiation for prevention of heterotopic ossification. The mechanism of radiotherapy responsible for the reduction of heterotopic ossification is unclear. The purpose of this study was to study an analogue model showing a time- and dose-dependent effect of radiation. Using cells of the defined embryonic mouse cell line C2C12, the influence of ionizing radiation on the Bmp-induced signal cascade leading to osteogenic differentiation was analyzed. Binding of iodinated Bmp2 to the receptors, Smad1 activation, and alkaline phosphatase (ALP) activity were determined in cells with or without irradiation. The cytotoxic effect of radiotherapy was evaluated using viability tests. Radiotherapy reduced formation of the Bmp2/Bmp receptor complex. This effect was dependent on dose. The phosphorylation (activation) of Smad1 decreased after irradiation in a time-dependent manner, whereas the level of total Smads was not influenced by radiotherapy. The ALP activity decreased after radiotherapy. A dose of 7 Gy delivered 6 h before or after incubation with Bmp resulted in about a 30% decrease in ALP activity. No signs of cytotoxic effects were observed within the time window studied using doses of 0 to 20 Gy. The time- and dose-dependent effect of radiotherapy for prevention of heterotopic ossification known from the results of clinical studies has an analogue in the C2C12 cell model. The primary mechanism of radiotherapy seems to be an influence on cellular responsiveness to the Bmp2-induced osteoblastic differentiation. The results suggest a down-regulation of the Bmp2/receptor complex.

Radiation-induced reduction of BMP-induced proteoglycan synthesis in an embryonal mesenchymal tissue equivalent using the chicken "limb bud" test

PURPOSE

Heterotopic ossification (HO) is a common complication following total hip replacement. Clinical studies showed the effectiveness of irradiation for prevention of heterotopic ossification. The mechanism of radiotherapy responsible for the reduction of heterotopic ossification is unclear. The purpose of this study was to find a suitable cell system, which can reproduce in-vitro data resulting from clinical in-vivo studies. The establishment of such a cell model allows detailed analyses of the mechanism of radiotherapy.

METHOD

The chicken limb bud test was used as an in-vitro model. The cells acquired by the limb bud test were irradiated with different doses (0 Gy, 3 Gy, 7 Gy, 10 Gy, 20 Gy). Irradiation was set either 1 hour before, or 1 or 3 days after BMP-2 incubation. The synthesis of proteoglycans (PGS) upon treatment with bone morphogenetic protein (BMP)-2 was measured in cells incubated with BMP-2 for 4 days followed by 35SO4(2-) labeling for 6 hours. Labeled proteoglycans were precipitated using Alcian blue and measured in a raytest radio-TLC analyzer. The incubation with BMP-2 was defined to correlate the in-vivo stimulus meaning the operation.

RESULTS

The proteoglycan synthesis was significantly reduced by irradiation 1 hour before or 1 day after BMP-2 incubation, if the dosage was at least 7 Gy. Higher doses than 7 Gy did not lead to lower proteoglycan levels. There was only a trend for a reduction of proteoglycan synthesis by 3 Gy irradiation, but no significant difference compared to the non-irradiated control. An irradiation 3 days after BMP-2 incubation had no effect on proteoglycan.

CONCLUSION

A dose and time dependent effect of radiation on BMP-2-induced proteoglycan synthesis was observed. Therefore the results of clinical in-vivo studies were reproduced exactly by the limb bud test. We established an in-vitro cell model to analyze the mechanism of the prevention of heterotopic ossification by radiotherapy on cellular or sub-cellular level.

p53 and Ki-67 as predictive markers for radiosensitivity in squamous cell carcinoma of the oral cavity? an immunohistochemical and clinicopathologic study

PURPOSE

Previously published data relating the expression of p53 and Ki-67 to radiation response in head and neck cancer are conflicting. This may be due to differences in patient selection and treatment modalities. In this study of a homogenous population of patients with oral cavity cancer, Ki-67 and p53 indices were correlated with histopathologically assessed tumor regression after preoperative radiochemotherapy and longterm outcome.

METHODS AND MATERIALS

Eighty-eight patients with squamous cell carcinoma of the oral cavity and treated between September 1985 and November 1995 by preoperative radiochemotherapy and definitive surgery were included in this analysis. By immunohistochemistry (IHC) the pre-irradiation expression of p53 and of Ki-67 were analyzed and correlated with the histopathologically proven tumor regression, overall survival and local control.

RESULTS

The overall 2- and 5-year survival rates were 76.5% and 63%, the locoregional control rates were 84% and 79%, respectively. After preoperative radiochemotherapy 29 patients (33%) showed complete tumor regression (ypT(0) classification). Survival and local control rates were significantly higher for patients showing ypT(0) classification than ypT(1-4) classification (p < 0.01). This effect was independent of pretreatment tumor classification in multivariate analysis. Pre-irradiation p53 status and Ki-67 index had no influence on tumor regression and clinical outcome in these patients.

CONCLUSION

Complete tumor regression after preoperative treatment is related to an improved outcome in combined modality treatment of oral cavity cancer. The presented study could not demonstrate an influence of p53 and Ki-67 status as detected by immunohistochemical staining on survival, local control, or tumor regression after radiochemotherapy.