[Radiotherapy using a combination of photons and protons for locally aggressive intracranial tumors. Preliminary results of protocol CPO 94-C1]

PURPOSE

From October 1993 through July 1998, 48 assessable adult patients with non-resectable aggressive intracranial tumors were treated by a combination of high dose photon + proton therapy at the Centre de Protonthérapie d'Orsay.

PATIENTS AND METHODS

Grade 1 and 4 gliomas were excluded. Patients benefited from a 3D dose calculation based on high-definition CT and MRI, a stereotactic positioning using implanted fiducial markers and a thermoplastic mask. Mean tumor dose ranged between 63 and 67 Gy delivered in five weekly sessions of 1.8 Gy in most patients, according to the histological types (doses in Co Gy Equivalent, with a mean proton-RBE of 1.1).

RESULTS

With a median 18-month follow-up (range: four-58 months), local control in tumors located in the envelopes and in the skull base was 97% (33/34), and in parenchymal tumors, 43% (6/14) only. Two patients (5%) presented with a clinically severe radiation-induced necrosis (temporal lobe and chiasm).

CONCLUSION

In our experience, high-dose radiation combining photons and protons is a safe and highly efficient procedure in selected malignancies of the skull base and envelopes.

Breast boost--why, how, when...?

BACKGROUND

Breast conservation management including tumorectomy or quadrantectomy and external beam radiotherapy with a dose of 45 to 50 Gy in the treatment of small breast carcinomas is generally accepted. The use of a radiation boost--in particular for specific subgroups--has not been clarified. With regard to the boost technique there is some controversy between groups emphasizing the value of electron boost treatment and groups pointing out the value of interstitial boost treatment. This controversy has become even more complicated as there is an increasing number of institutions reporting the use of HDR interstitial brachytherapy for boost treatment. The most critical issue with regard to interstitial HDR brachytherapy is the assumed serious long-term morbidity after a high single radiation dose as used in HDR-treatments.

METHODS AND RESULTS

This article gives a perspective and recommendations on some aspects of this issue (indication, timing, target volume, dose and dose rate).

CONCLUSION

More information about the indication for a boost is to be expected from the EORTC trial 22881/10882. Careful selection of treatment procedures for specific subgroups of patients and refinement in surgical procedures and radiotherapy techniques may be useful in improving the clinical and cosmetic results in breast conservation therapy. Prospective trials comparing on the one hand different boost techniques and on the other hand particular morphologic criteria in treatments with boost and without boost are needed to give more detailed recommendations for boost indications and for boost techniques.

[Conformal radiotherapy of brain tumors]

Conformal irradiation of brain tumours is based on the three-dimensional reconstruction of the targeted volumes and at-risk organ images, the three-dimensional calculation of the dose distribution and a treatment device (immobilisation, beam energy, collimation, etc.) adapted to the high precision required by the procedure. Each step requires an appropriate methodology and a quality insurance program. Specific difficulties in brain tumour management are related to GTV and CTV definition depending upon the histological type, the quality of the surgical resection and the medical team. Clinical studies have reported dose escalation trials, mostly in high-grade gliomas and tumours at the base of the skull. Clinical data are now providing a better knowledge of the tolerance of normal tissues. As for small tumours, the implementation of beam intensity modulation is likely to narrow the gap between conformal and stereotaxic radiotherapy.

[First treatment for brain metastases by stereotactic radiosurgery]

Local control of brain metastases is better with first treatment by stereotactic radiosurgery than with radiosurgery for recurrence. We reported a retrospective analysis of the influence of clinical and technical factors on local control and survival after radiosurgery realised in first intention. From January 1994 to December 1997, 26 patients presenting with 43 metastases underwent radiosurgery. The median age was 61 years and the median Karnofsky index 70. Primary sites included: lung (12 patients), kidney (7 patients), breast (2 patients), colon (1 patient), melanoma (2 patients), osteosarcoma (1 patient), it was unknown for one patient. Seven patients had extracranial metastases. Twenty-one sessions of radiosurgery have been realized for one metastase, and 9 for two, three or four lesions. The median diameter was 21 mm and the median volume 1.8 cm3. The median peripheral dose to the lesion was 14 Gy, and the median dose at the isocenter 20 Gy. Forty-two metastases were evaluable for response analysis. The overall local control rate was 90.5% and the 1-year, 2- and 3-year actuarial rates were 85% and 75%. In univariate analysis, theorical radioresistance was significantly associated with better local control (100% versus 77%, p < 0.05). All patients were evaluable for survival. The median survival rate was 15 months. Four patients had a symptomatic oedema (RTOG grade II). Two lesions have required a surgical excision. In conclusion, low dose radiosurgery (14 Gy delivered at the periphery of metastasis) can be proposed in first intention for brain metastases, in particularly for theorical radioresistant lesions.

Treatment of malignant gliomas in the elderly

The benefit of standard treatment of malignant glioma in older patients is debated. In order to assess the effect of a combination of surgery, radiotherapy and chemotherapy on survival of elderly patients with high grade gliomas, 30 consecutive patients older than 70 years with malignant supratentorial gliomas were studied between 9/93 and 9/96. Median age was 73 years (70-79). The mean Karnofsky performance status (KPS) was 66 (30-100). Patients underwent maximum possible surgery, followed by a course of radiotherapy (45 Gy/25 fractions/5 weeks) with 3 or 4 orthogonal beams and a 2 cm margin around the tumor bed. The administration of chemotherapy was left at the discretion of the responsible physician and 12 patients received reduced dose nitrosourea-based chemotherapy. The overall median survival was 36 weeks. The median time to progression was 26 weeks. Three months after surgery, 26 patients were alive, 5 were in complete response, 2 in partial response and 10 were stabilized. Preradiotherapy KPS was the only significant prognostic factor with a median survival of 40 weeks in patients with KPS > or = 70 and 25 weeks when KPS was < 70 (logrank test, p = 0.05). In responding and stable patients (57% of the group) the median KPS was 68 and 66 at 1 and 3 months after the completion of radiotherapy. There was no case of radiotherapy-induced dementia with this regimen. Four out of 12 patients who received chemotherapy, experienced WHO grade 3/4 hematotoxicity. This study suggest that some patients older than 70 years with KPS > or = 70 may benefit from the treatment of malignant gliomas with surgery followed by reduced dose of limited field radiotherapy. Further studies are needed to define the most appropriate dose of radiotherapy and to evaluate further the risk/benefit ratio of a reduced dose chemotherapy in this population.

Treatment of squamous cell anal canal carcinoma with pulsed dose rate brachytherapy. Feasibility study of a French cooperative group

BACKGROUND AND PURPOSE

To evaluate the feasibility of pulsed dose rate (PDR) brochytherapy in squamous cell anal canal carcinoma (SCACC).

MATERIALS AND METHODS

In this study a series of 19 patients with SCACC were included between 1995 and 1997. All patients were treated with curative intent with external beam radiotherapy (EBRT) (44-50 Gy) and one or two cycles of concomitant fluorouracilcisplatinum. After a gap of 2-3 weeks PDR interstitial brachytherapy was performed with a rigid needles technique. The dose was between 10-25 Gy (PARIS system).

RESULTS

All patients are alive. No severe grade 3-4 toxicity was encountered. One local relapse one metastatis were seen in two distinct patients. There was no dysfunction of the after loading machine.

CONCLUSION

The feasibility of PDR brachytherapy appears good in SCACC. It is an attractive alternative to low dose rate brachytherapy.

[The centenary of the discovery of radium]

Henri Becquerel presented the discovery of radium by Pierre and Marie Curie at the Paris Académie des Sciences on 26th December 1898. One century later, radium has been abandoned, mainly for the reason of radiation safety concerns. It is, however, likely that modern techniques of brachytherapy are the successors of those designed for radium sources, and that radium has cured thousands and thousands patients all over the word for about 80 years. The history of discovery and medical use of radium is summarised.

How to optimize therapeutic ratio in brachytherapy of head and neck squamous cell carcinoma?

Considerable experience has been accumulated with low dose rate (LDR) brachytherapy in the treatment of squamous cell carcinoma of the oral cavity and oropharynx, 4 cm or less in diameter. Recent analysis of large clinical series provided data indicating that modalities of LDR brachytherapy should be optimized in treating these tumours for increasing therapeutic ratio. LDR brachytherapy is now challenged by high dose rate (HDR) brachytherapy and pulsed dose rate (PDR) brachytherapy. Preliminary results obtained with the last two modalities are discussed in comparison with those achieved with LDR brachytherapy.

The centenary of discovery of radium

Henri Becquerel presented the discovery of radium by Pierre and Marie Curie at the Paris Academy of Science on 26th December 1898. One century later, radium has been abandoned, mainly for radiation protection difficulties. It is, however, likely that modern techniques of brachytherapy have inherited to those designed for radium sources, and that radium has cured thousands and thousands patients all over the world for about eighty years. The history of discovery and medical use of radium is summarised.

[Role of intravascular brachytherapy in the prevention of vascular restenosis after angioplasty]

About 30% of patients who underwent percutaneous transluminal coronary angioplasty show evidence of restenosis, which appears to be independent of the angioplasty method used. The restenosis is due of two factors, firstly migration of smooth vascular muscle cells of the vascular media to the intima and multiplication which lead to the formation of a neo-intima. Irradiation limits the proliferation by acting of the cells in the mitotic stage. The vascular target volume is not very thick and is difficult to define it, that why brachytherapy seems to be the best procedure to prevent restenosis. However, the development of this treatment present many difficulties. Different irradiation techniques have been studied. Such techniques include catheter containing radioactive sealed source, radioactive stent, or balloon containing radioactive liquid inside. Each of these methods have their own advantages, inconveniences, problems and risks. Radioisotope may be either beta or gamma emitters. Gamma emitter presents problems for radioprotection but the satisfactory dose distribution may be difficult to obtain using beta emitter. Choice of dose, dose rate and delay between the end of angioplasty and the beginning of brachytherapy is subject to some discuss. Animal experiments using radioisotope have shown reduction in cell proliferation. Human trials showed feasibility, safety of the method and real impact on restenosis prevention. However, long-term efficacy has not been proved because the follow-up of the patients is too short. A randomized trial of 192Ir brachytherapy for prevention of restenosis has recently shown the efficacy in short and median term. However, long term efficiency and secondary effects have not yet been established as the follow up time of this study is still too short. That is why, collaboration between cardiologists and radiotherapists and physicists is indispensable to enable the development of an optimal technique.

[Late effects of ionizing radiations on the vulva, vagina and uterus]

Reporting and scoring complications after radiotherapy of gynaecological cancers is difficult because of the variety of treatment techniques involved. Use of an international classification is necessary to compare results obtained in series of patients treated in different institutions. An international group of experts designed in the early nineties the so-called French-Italian glossary. This classification of late effects is now completed with the new LENT SOMA scales. This paper contains details of these late changes, including their pathophysiology, clinical syndromes, potential treatment, and prevention.

[Late effects of ionizing radiations on head and neck region tissues]

Numerous structures are included in the irradiated volume of patients presenting with head and neck cancer: skin, mucosa, bone, teeth, cartilage, muscles, salivary glands, etc. Curative intent treatment of such tumours requires aggressive approach which can lead to severe sequellae. These sequellae are in most cases dose-dependent and volume-dependent. However, an appropriate technique might decrease the severity of such sequellae. Details of these late changes are presented, including their pathophysiology, clinical syndromes, potential treatment, and prevention.