Modulation d’intensité en radiothérapie mammaire : développement d’une méthode innovante de champ dans le champ à l’institut Gustave-Roussy

Purpose

To assess the potential dosimetric gain of presegmentation modulated radiotherapy (OAPS, DosiSoft™) of breast, compared to routine 3D conformal radiotherapy.

Patients and methods

Twenty patients treated with conservative surgery for breast cancer (9 right and 11 left sided) with various breast volume (median 537 cm³; range [100–1049 cm³]) have been selected. For each patient, we have delineated a breast volume and a compensation volume (target volumes), as well as organs at risk (lungs and heart). Two treatment plans have been generated: one using the routine 3D conformal technique and the other with the presegmentation algorithm of DosiSoft™ (OAPS). The dose distribution were analyzed using the conformity index for target volumes, mean dose and V30 Gy for the heart, and mean dose, V20 Gy and V30 Gy for lungs.

Results

Over the 20 patients, the conformity index increased from 0.897 with routine technique to 0.978 with OAPS (P < 0,0001). For heart and lung, OAPS decreased irradiation (mean cardiac dose 1,3 vs 1,6 Gy [P < 0,0001] and pulmonary V20 Gy 6,6 vs 7,1 [P < 0,0001]).

Conclusion

OAPS (DosiSoft™) is an original method of segmentation of breast. It is automatic, fast and easy, and is able to increase the conformity index, while sparing organ at risk.     

De la radiothérapie guidée par l’image à la radiothérapie guidée par la dose

Purpose

In case of tumour displacement, image-guided radiotherapy (IGRT) based on the use of cone beam CT (tomographie conique) allows replacing the tumour under the accelerator by rigid registration. Anatomical deformations require however replanning, involving an estimation of the cumulative dose, session after session. This is the objective of this study.

Patients and methods

Two examples of arc-intensity modulated radiotherapy are presented: a case of prostate cancer (total dose = 80 Gy) with tomographie conique (daily prostate registration) and one head and neck cancer (70 Gy). For the head and neck cancer, the patient had a weekly scanner allowing a dose distribution calculation. The cumulative dose was calculated per voxel on the planning CT after deformation of the dose distribution (with trilinear interpolation) following the transformation given by a non-rigid registration step (Demons registration method) from: either the tomographie conique (prostate), or the weekly CT. The cumulative dose was eventually compared with the planned dose.

Results

In cases of prostate irradiation, the “cumulative” dose corresponded to the planned dose to the prostate. At the last week of irradiation, it was above the planned dose for the rectum and bladder. The volume of rectal wall receiving more than 50 Gy (V50) was 20% at the planning and 26% at the end of treatment, increasing the risk of rectal toxicity (NTCP) of 14%. For the bladder wall, V50 were 73% and 82%, respectively. In head and neck, the “cumulative” dose to the parotid exceeded the planned dose (mean dose increasing from 46 Gy to 54 Gy) from the 5th week of irradiation on, suggesting the need for replanning within the first 5 weeks of radiotherapy.

Conclusion

The deformable registration estimates the cumulative dose delivered in the different anatomical structures. Validation on digital and physical phantoms is however required before clinical evaluation.     

Rôle de l’irradiation locorégionale adjuvante en l’absence d’envahissement ganglionnaire après chimiothérapie néoadjuvante, mastectomie totale et lymphadénectomie axillaire pour un cancer du sein. Expérience de l’hôpital René-Huguenin–institut Curie

Purpose

Neoadjuvant chemotherapy generally induces significant changes in the pathological extent of disease and challenges the standard indications of adjuvant postmastectomy radiation therapy. We retrospectively evaluated the impact of postmastectomy radiation therapy in breast cancer patients with negative lymph nodes (pN0) after neoadjuvant chemotherapy.

Patients and materials

Among 1054 breast cancer patients treated with neoadjuvant chemotherapy in our institution between 1990 and 2004, 134 patients had pN0 status after neoadjuvant chemotherapy and mastectomy. Demographic data, tumor characteristics, metastatic sites, and treatments were prospectively recorded. The impact of postmastectomy radiation therapy on locoregional recurrence-free survival and overall survival was evaluated by multivariate analysis including known prognostic factors.

Results

Among 134 eligible patients, 78 patients (58.2%) received postmastectomy radiation therapy, and 56 patients (41.8%) did not. With a median follow-up time of 91.4 months, the 10-year locoregional recurrence-free survival and overall survival rates were 96.2% and 77.2% with postmastectomy radiation therapy and 86.8% and 87.7% without radiation therapy, respectively (no significant difference). In multivariate analysis, there was a trend towards poorer overall survival among patients who did not have a pathologically complete primary tumour response after neoadjuvant chemotherapy (hazard ratio [HR], 6.65; 95% CI, 0.82–54.12; P = 0.076). Postmastectomy radiation therapy had no effect on either locoregional recurrence-free survival (HR, 0.37; 95% CI, 0.09–1.61; P = 0.18) or overall survival (HR, 2.06; 95% CI, 0.71–6; P = 0.18). There was a trend towards poorer overall survival among patients who did not have pathologically complete in-breast tumour response after neoadjuvant chemotherapy (HR, 6.65; 95% CI, 0.82–54.12; P = 0.076).

Conclusions

This retrospective study showed no increase in the risk of distant metastasis, locoregional recurrence or death when postmastectomy radiation therapy was omitted in breast cancer patients with pN0 status after neoadjuvant chemotherapy and mastectomy. Whether the omission of postmastectomy radiation therapy is acceptable for these patients should be addressed prospectively.     

Haute dose dans la prostate par radiothérapie guidée par l’image : apport de l’arcthérapie avec modulation d’intensité du faisceau

PurposeTo compare two Intensity Modulated Radiation Therapy (IMRT) techniques for prostate cancer: the Volumetric Modulated Arc Therapy (VMAT) and the “Step and Shoot” technique (S&;S).Materials and methodsVMAT and S&;S plans (RX 18 MV) were created and compared (Wilcoxon test) for 10 patients. The dosimetric goal of both treatments was to deliver 46 Gy to the seminal vesicles and 80 Gy to the prostate, while respecting the dose constrains in the organs at risk of toxicity. For one patient, the two techniques were compared for dose painting and escalation in target volumes defined on MRI and registered thanks to intraprostatic fiducials.ResultsVMAT, compared to S&;S, offered: an increase of the PTV2s (prostate) volume receiving 77 to 80 Gy and a decrease of V₈₂ and V₈₃; a decrease of V₄ to V₆, V₁₆ to V₂₃, and V₆₉ to V₇₃ for the rectal wall; a decrease of V₂₅ for the bladder wall; a decrease of V₂₁ to V₄₃ for the femoral heads; a decrease of V₂₆ to V₄₄ and V₇₂ to V₈₀ but an increase of V₁ to V₂₁ and V₄₉ to V₆₀ for the healthy tissues. The Conformal Index “COIN” was better with VMAT than S&;S (0.60 to 0.66). The delivered MU were significantly reduced with VMAT (8% mean) as well as the delivery time (4 min to 1.5 min). VMAT allowed delivering theorically 90 Gy in the peripheral zone and 100 Gy in the tumor.ConclusionIn case of prostate irradiation, VMAT shows improvement compared with S&;S. In particular, organs at risk are better spared, the delivery time is shortened and the number of delivered UM is decreased.     

Hormonoradiothérapie exclusive dans la prise en charge du cancer du sein de la personne âgée : cas clinique et revue de la littérature des schémas hypofractionnés

Normofractionated radiotherapy is standard for adjuvant management of patients treated with breast conservative surgery for breast cancer. However, many elderly patients are not eligible to such strategy, either because of concurrent diseases, or because the tumor is inoperable. Several protocols of exclusive radiotherapy have been reported in the literature, frequently using hypofractionated radiotherapy and endocrine therapy. We report a case of a patient treated with exclusive endocrine and radiotherapy and address the state of the art on hypofractionated schemes for the management of elderly breast cancer patients. While hypofractionated radiotherapy does not compromise the oncologic or cosmetic outcome, there is no prospective data that assesses the place of radiotherapy for the exclusive treatment of elderly patients. This strategy should be further assessed in clinical randomized trial.     

Dentalmaps : un outil pratique pour chirurgiens dentistes et radiothérapeutes pour l’estimation de la dose reçue aux dents, mandibule et maxillaire et du risque de complications postradiques en cas de soins dentaires

Purpose

Manual delineation of dental structures is too time-consuming to be feasible in routine practice. Information on dose risk levels is crucial for dentists following irradiation of the head and neck to avoid postextraction osteoradionecrosis based on empirical dose-effects data established on bidimensional radiation therapy plans.

Material and methods

We present an automatic atlas-based segmentation framework of the dental structures, called Dentalmaps, constructed from a patient image-segmentation database.

Results

This framework is accurate (within 2 Gy accuracy) and relevant for the routine use. It has the potential to guide dental care in the context of new irradiation techniques.

Conclusion

This tool provides a user-friendly interface for dentists and radiation oncologists in the context of irradiated head and neck cancer patients. It will likely improve the knowledge of dose-effect correlations for dental complications and osteoradionecrosis.     

Radiothérapie en conditions stéréotaxiques des gliomes de haut grade : une revue de la littérature

The purpose of this literature systematic review was the use of stereotactic radiotherapy in glioma. Research was performed in Medline/PubMed and associated references found in published articles without publication date limit. The quality of series is variable and many biases can be evidenced. Only two randomized trials have been published using stereotactic radiotherapy for up-front treatment. There is a lack of evidence of survival advantages to use this treatment at the time of diagnosis or relapse. There is also insufficient evidence regarding the benefice/harms in the use of stereotactic fractionated radiation therapy for patients with glioma. No recommendations can be enounced. Stereotactic irradiation as boost in primary diagnosed glioma or relapsed tumour is not associated with survival improvement. For relapsed patients, treatment needs to be discussed according to the other treatment options.     

Rôle de l’irradiation ganglionnaire chez les patientes indemnes d’envahissement ganglionnaire après chimiothérapie néoadjuvante pour un cancer du sein : expérience du centre René-Huguenin

PurposeNeoadjuvant chemotherapy generally induces significant changes in the pathological extent of disease. This potential down-staging challenges the standard indications of adjuvant radiation therapy. We assessed the utility of lymph node irradiation in breast cancer patients with pathological N0 status (pN0) after neoadjuvant chemotherapy and breast-conserving surgery.Patients and materialsAmong 1054 breast cancer patients treated with neoadjuvant chemotherapy in our institution between 1990 and 2004, 248 patients with clinical N0 or N1-N2 lymph node status at diagnosis had pN0 status after neoadjuvant chemotherapy and breast-conserving surgery. Cox regression analysis was used to identify factors influencing locoregional recurrence-free survival, disease-free survival and overall survival.ResultsAll 248 patients received breast irradiation, and 158 patients (63.7%) also received lymph node irradiation. With a median follow-up of 88 months, the 5-year locoregional recurrence-free survival and overall survival rates were respectively 89.4% and 88.7% with lymph node irradiation and 86.2% and 92% without lymph node irradiation (no significant difference). Survival was poorer among patients who did not have a pathological complete primary tumor response (pCR) (hazards ratio [HR] = 3.05; 95% CI, 1.17 to 7.99) and in patients with N1-N2 clinical status at diagnosis ([HR] = 2.24; 95% CI, 1.15 to 4.36). Lymph node irradiation did not significantly affect survival.ConclusionsRelative to combined breast and local lymph node irradiation, isolated breast irradiation does not appear to be associated with a higher risk of locoregional relapse or death among breast cancer patients with pN0 status after neoadjuvant chemotherapy. These results need to be confirmed in a prospective study.     

Radiothérapie stéréotaxique de carcinomes bronchiques primitifs : suivi non invasif de la cible en temps réel

PurposeStereotactic radiation therapy using the CyberKnife^® has been introduced in France in 2006. Two treatment modalities are currently available: the first one (Synchrony^®) is a real-time fiducial-based target tracking system, while the other (Xsight Lung Tracking [XLT] System^®) is completely fiducial-free.Patients and methodsSixty-eight patients were treated for a pulmonary tumor between June 2007 and November 2009. Since august 2008, the XLT System^® was used for 26 patients. We report the necessary conditions for the XLT System (position, laterality and size of the tumor), the toxicity and outcome of this treatment.ResultsTwenty-two patients were analyzed. Median follow-up was 6 months (min = 3; max = 16). Local control rate was 100%. The main toxicity was grade grade 1 pulmonary alveolitis (27%). No grade 3 or 4 toxicities were reported.ConclusionThe high local control rate and low toxicity obtained with the CyberKnife^® XLT System^® suggest that such treatment is an alternative for inoperable patients.