R. Kabacińska

Results of interstitial HDR brachytherapy for cancer of the lower lip

Summary Background HDR brachytherapy has been employed in the treatment of cancers in numerous locations around the body, however, few publications have dealt with primary carcinomas of the head and neck. To our knowledge, only one paper concerns the use of this technique in the treatment of cancers of the lower lip. Furthermore, the recommendations given by the American Association of Brachytherapy do not appear to elaborate on the subject. Aim To analyse the treatment of lower lip carcinoma by interstitial HDR brachytherapy. Materials/Methods Retrospective analysis of the results of treatment was carried out among a group of 24 consecutive patients, of whom 18 were treated by brachytherapy alone while 6 others were treated after surgery. Fifteen patients were classified as T1, nine patients as T2. 23 patients were classified as N0 and one as N1. Each patient had histologically confirmed squamous cell carcinoma. Radiotherapy involved interstitial, high dose rate brachytherapy with an iridium-192 source. Post-operative brachytherapy was indicated in cases of microscopically incomplete excision. The dose was determined using the Paris method, the reference dose being 80% or at a point 3–5 mm from the macroscopic lesion or tumour bed. The mean total dose was 35 Gy, the mean number of fractions was 7, and the mean fraction dose was 5.7 Gy. The total treatment time was 12 days, on average, whereas the mean follow-up was 32 months. Results Local control was obtained after 24 months in 21 patients (87.5%). All patients developed a severe early reaction. Three patients with mouth corner infiltration (100%) failed to show complete regression. Two of these patients underwent additional irradiation to the residual lesion, resulting in cures. The third patient underwent successful surgical treatment. The cosmetic and functional effect was very good. Conclusuions Interstitial HDR brachytherapy is an effective and safe method for the treatment of carcinoma in the lower lip.

Dose estimation for different skin models in interstitial breast brachytherapy

Purpose Skin is a major organ at risk in breast-conserving therapy (BCT). The American Brachytherapy Society (ABS) recommendations require monitoring of maximum dose received, however, there is no unambiguous way of skin contouring provided. The purpose of this study was to compare the doses received by the skin in different models. Material and methods Standard treatment plans of 20 patients who underwent interstitial breast brachytherapy were analyzed. Every patient had a new treatment plan prepared according to Paris system and had skin contoured in three different ways. The first model, Skin 2 mm, corresponds to the dermatological breast skin thickness and is reaching 2 mm into an external patient contour. It was rejected in a further analysis, because of distinct discontinuities in contouring. The second model, Skin 4 mm, replaced Skin 2 mm, and is reaching 2 mm inside and 2 mm outside of the External contour. The third model, Skin EXT, is created on the External contour and it expands 4 mm outside. Doses received by the most exposed 0.1 cc, 1 cc, 2 cc, and the maximum doses for Skin 4 mm and Skin EXT were compared. Results Mean, median, maximum, and standard deviation of percentage dose difference between Skin EXT and Skin 4 mm for the most exposed 0.1 cc (D0.1cc) of skin were 18.01%, 17.20%, 27.84%, and 4.01%, respectively. All differences were statistically significant (p < 0.05). Conclusions Monitoring of doses received by skin is necessary to avoid complications and obtain a satisfactory cosmetic effect. It is difficult to assess the compatibility of treatment plans with recommendations, while there is no unambiguous way of skin contouring. Especially, if a mean difference of doses between two models of skin contouring is 18% for the most exposed 0.1 cc and can reach almost 28% in some cases. Differences of this magnitude can result in skin complications during BCT.

Does interstitial HDR brachytherapy for breast cancer increase soft tissue fibrosis

Summary Aim To analyze the physical parameters of interstitial HDR brachytherapy and their influence on the risk of soft tissue fibrosis. Materials/Methods A retrospective analysis of 54 breast cancer patients treated between 1994–1999 in the Brachytherapy Department of the Oncological Centre in Bydgoszcz was performed. Minimum follow up period was 41 months and the maximum was 89 months. The mean follow up period was 65 months. Owing to statiscally significant differences between the groups, when compared to a normal distribution, the U Mann-Whitney non-parametrical test was used as the method for comparison. Results Out of the nine parameters analysed, three were found to be associated with increased risk of fibrosis occurrence. Reference volumes V100, V150 and V200 showed statistically significant differences (p Conclusions In breast conserving therapy a number of parameters influence the results of treatment. Our own studies have shown that among the risk factors responsible for fibrosis are: reference volume V100 (the volume of tissue surrounded by 100% isodose), V150 (volume of tissue surrounded by 150% isodose) and V200 (volume of tissue surrounded by 200% isodose).

Estimation of the α/β ratio for lower lip cancer treated with interstitial HDR brachytherapy

Summary Background A standard linear-quadratic (LQ) model is now routinely used for clinical data analysis and the prediction of the clinical effect of radiotherapy. The typical α/β values suggested in the literature range from 10 to 20Gy for most tumours and early responding normal tissues, and from 2 to 5Gy for late responding tissues. Aim The estimation of α/β ratio values for planoepithelial lower lip cancer. Materials/Methods The clinical material is based on the records of 25 patients undergoing radical treatment with interstitial brachytherapy: 19 patients were administered brachytherapy exclusively and 6 patients were treated postoperatively. The following stage arrangement was applied: T 1 in 15 pts, T 2 in 9 pts, N 0 in 24 pts and N 1 only in one T 2 patient. Radiotherapy was based on HDR brachytherapy using the interstitial technique. Patients with positive margins after surgery were qualified for postoperative brachytherapy. The dose was either specified at the reference 80% isodose according to the Paris System or points calculated 3-5 mm from the macroscopic tumour. The average total dose was 38.3Gy, the number of fractions being 7 and the fraction dose 5.3Gy. The overall treatment time was 12 days. The average follow-up period was 30 months. A standard probit regression in conjunction with a linear-quadratic model was used. Results The estimated value of the α/β ratio for lip cancer was 12Gy (±3.72 * 10 −10 95% CI). Conclusions The estimated α/β ratio is consistent with α/β ratios published for squamous cell head and neck cancers.

An analysis of outcomes, after re-irradiation by HDR (high-dose-rate) brachytherapy, among patients with locally recurrent nasopharyngeal carcinoma (NPC)☆

Summary Background Despite aggressive treatment with radiotherapy, which is often combined with chemotherapy, local persistence occurs in 18–40% of patients with nasopharyngeal carcinoma. Brachytherapy is one of the methods for the re-treatment of patients with locally recurrent nasopharyngeal carcinoma. Aim The aim of this paper was to evaluate the effectiveness of HDR (high-dose-rate) treatment of patients with locally recurrent nasopharyngeal carcinoma. Materials/Methods The study took the form of a retrospective analysis and included a group of 28 patients treated in the Brachytherapy Department of the Oncology Centre in Bydgoszcz during the years 1995–2000. Brachytherapy was carried out using a Rotterdam applicator and the MicroSelectron HDR apparatus produced by Nucletron. Irradiation was based on doses of 36 Gy, i.e. 6 Gy applied once a week, and 51 Gy i.e. 3 Gy applied twice a week. This paper presents recovery probability, overall survival and recurrence-free survival within the analysed group of patients. Results The results obtained prove intracavitary HDR (high-dose-rate) brachytherapy to be a viable method for the treatment of patients with recurring nasopharyngeal carcinoma. Conclusions The higher the total dose applied by means of brachytherapy, the greater the chance of locally successful treatment, moreover, the time that elapses before recurrence is considered to be an important factor influencing recurrence-free survival time.

Wpływ optymalizacji geometrycznej na wybrane parametry rozkładu dawki na przykładzie brachyterapii u chorych na raka gruczołu piersiowego

Streszczenie Cel pracy Analiza parametrow rozkladu dawki dla dwuplaszczyznowych implantow w gruczole piersiowym z zastosowaniem optymalizacji geometrycznej. Material i metoda Analizie poddano parametry rozkladu dawki oraz indeks jakości rozkladu dawki QI dla 20 dwuplaszczyznowych aplikacji wykonanych w naszej praktyce klinicznej. Wyznaczono nastepujące parametry: objetośc referencyjną V 100 , objetośc napromienianą V 50 , objetośc wysokiej dawki V 200 . Parametry te analizowano w przypadku zastosowania optymalizacji geometrycznej rozkladu dawki i bez optymalizacji. Wnioski Optymalizacja geometryczna powoduje wzrost objetości referencyjnej V 100 . W porownaniu z klasycznym implantem nieoptymalizowanym, zgodnym z zasadami systemu Paryskiego brachyterapii wewnątrztkankowej, optymalizacja ta pozwala ograniczyc dlugośc aktywną implantu i nie rozszerzac jej poza obszar targetu. Jest to korzystne w przypadku implantow piersi, gdzie obszar targetu graniczy ze skorą.

Transition from Paris dosimetry system to 3D image-guided planning in interstitial breast brachytherapy

Purpose The purpose of this study is to evaluate our first experience with 3D image-guided breast brachytherapy and to compare dose distribution parameters between Paris dosimetry system (PDS) and image-based plans. Material and methods First 49 breast cancer patients treated with 3D high-dose-rate interstitial brachytherapy as a boost were selected for the study. Every patient underwent computed tomography, and the planning target volume (PTV) and organs at risk (OAR) were outlined. Two treatment plans were created for every patient. First, based on a Paris dosimetry system (PDS), and the second one, imaged-based plan with graphical optimization (OPT). The reference isodose in PDS implants was 85%, whereas in OPT plans the isodose was chosen to obtain proper target coverage. Dose and volume parameters (D90, D100, V90, V100), doses at OARs, total reference air kerma (TRAK), and quality assurance parameters: dose nonuniformity ratio (DNR), dose homogeneity index (DHI), and conformity index (COIN) were used for a comparison of both plans. Results The mean number of catheters was 7 but the mean for 20 first patients was 5 and almost 9 for the next 29 patients. The mean value of prescribed isodose for OPT plans was 73%. The mean D90 was 88.2% and 105.8%, the D100 was 59.8% and 75.7%, the VPTV90 was 88.6% and 98.1%, the VPTV100 was 79.9% and 98.9%, and the TRAK was 0.00375 Gym–1 and 0.00439 Gym–1 for the PDS and OPT plans, respectively. The mean DNR was 0.29 and 0.42, the DHI was 0.71 and 0.58, and the COIN was 0.68 and 0.76, respectively. Conclusions The target coverage in image-guided plans (OPT) was significantly higher than in PDS plans but the dose homogeneity was worse. Also, the value of TRAK increased because of change of prescribing isodose. The learning curve slightly affected our results.

Preliminary results of linac-based radiosurgery in arteriovenous malformations and cerebral tumours in the Oncology Centre in Bydgoszcz

Aim of the study Efficacy of stereotactic radiosurgery (SRS) in the treatment in cerebral AVMs, mennigiomas, metastases, acoustic neuromas and recurrent anaplastic gliomas is well documented. The object of this work was the analysis of the results of the treatment of AVM and selected cerebral lesions with linear accelerator-based stereotactic radiosurgery. Material and methods The lesions included: 12 AVMs, 2 cavernomas, 27 meningiomas, 16 metastases, 5 acoustic neuromas, 16 gliomas in 78 patients. A mean radiation dose of 16Gy was delivered to the tumour or AVM margin and 12Gy to the tumours located in a ponto-cerebellar angle. Follow-up was 18 months. Results Control of tumour growth or AVM was achieved in all cases after 6 months and radiological regression was observed in 20 cases after 12 months. The best results were noted in AVMs, meningiomas and neuromas.There were no new permanent deficits nor complications after radiosurgery requiring medicamentation. Conclusions Organization of SRS in Oncological Center in Bydgoszcz involving close co-operation of radiotherapist, neurosurgeon and physicist in the process of qualification and treatment planning is based on the best global standards. Preliminary results of treatment are consistent with the literature data. A longer follow-up is required to determine the long term efficacy and the toxicity of this treatment in our institution.

Clinical Investigations Original article Interstitial brachytherapy for penile cancer: the experience of Oncology Centre in Bydgoszcz

Purpose The aim of this work was to analyze the treatment results and complications of patients with penile cancer treated in our centre. Material and methods Thirty three patients were included in this retrospective research. The average age was 62. All patients underwent brachytherapy HDR or PDR procedures using a remote-after-loading system with iridium source. Results Average follow-up was 60 months. Complete remission was observed in 24 patients (72.7%) out of the whole group. Locoregional and distant recurrences were noted in 9 patients (27.3%). In all patients 5-year overall and disease free survival were 84.9% and 75.4%, respectively. The 5-year locoregional control rate was 78.8%. Conclusion Radical brachytherapy could possibly be a good treatment option in selected patients with T1-3 penile cancer and lesions smaller than 4 cm in diameter.

Evaluation of spinal cord risk during HDR brachytherapy in patients with nasopharyngeal cancer

Summary Aim Use of Rotterdam applicators was analysed for the purpose of ascertaining the average dose to the spinal cord at the point of greatest load. Materials/Methods 20 procedures carried out on patients treated in the brachytherapy department were evaluated. Rotterdam nosopharynx applicators were positioned and localised according to the “box technique”. The radiographs were used to reconstruct the applicator in PLATO NPS version 14.1.3 treatment planning system. The position of spinal cord points were inserted according to the radiographs. The highest-loaded points were chosen to analyze. Results Points were localized (along the cord) to within an average accuracy of 0.52 mm. A comparison of doses in the cord at these points was carried out and the average dose using geometrical optimization (on distance) was 19.7% of the reference dose while without optimisation the average was 18.7% of the reference dose. Conclusions From the study undertaken, it appears that the calculated doses in the spinal cord, at the points of greatest load, are as described in the published data. The Rotterdam applicator may be used equally for radical treatment and for locally increasing the dose (boost) because of an acceptable spinal cord dose.