Dosimetric comparison of 3-dimensional conformal and field-in-field radiotherapy techniques for the adjuvant treatment of early stage endometrial cancer

BACKGROUND

The purpose of this study is to compare field-in-field radiotherapy (FIF) with conformal radiotherapy (CRT) in terms of dosimetric benefits for early stage endometrial cancer patients.

MATERIALS AND METHODS

Ten consecutive early stage endometrial cancer patients who underwent adjuvant external beam radiotherapy were included in the study. For each patient, two different treatment plans were created. FIF and CRT plans were compared for doses in the planning target volume (PTV), the organ at risk (OAR) volumes including rectum, bladder, bowel, bilateral femurs and bone marrow, the dose homogeneity index, and the monitor unit counts required for the treatment.

RESULTS

The FIF technique significantly reduced the maximum dose of the PTV, rectum, bladder, bowel, left femur, right femur and bone marrow (p values were: <0.001, 0.031, 0.003, <0.001, 0.001, 0.001 and <0.001 respectively). When the OAR volumes irradiated with >30 and >45 Gy were compared, the results were in favor of the FIF technique. The volumes of rectum, bladder, bowel, left femur, right femur and bone marrow receiving more than the prescription dose of 45 Gy were significantly reduced with FIF technique (p values were 0.016, 0.039, 0.01, 0.04, 0.037 and 0.01 respectively). The dose homogeneity index (DHI) was significantly improved with FIF technique (p < 0.001).

CONCLUSIONS

FIF allowed more homogeneous dose distribution in the PTV and reduced the doses received by OAR. Considering the lower maximum doses in the OAR and PTV, FIF technique seems to be more advantageous than CRT during adjuvant radiotherapy for early stage endometrial cancer patients.

Radiation pneumonitis in breast cancer patients who received radiotherapy using the partially wide tangent technique after breast conserving surgery

Purpose

We assessed the risk of radiation pneumonitis (RP) in terms of dosimetric parameters in breast cancer patients, who received radiotherapy using the partially wide tangent technique (PWT), following breast conservation surgery (BCS).

Methods

We analyzed the data from 100 breast cancer patients who underwent radiotherapy using PWT. The entire breast, supraclavicular lymph node, and internal mammary lymph node (IMN) were irradiated with 50.4 Gy in 28 fractions. RP was scored on a scale of 0 to 5, based on Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity criteria. The dosimetric parameters, used in analysis for the ipsilateral lung, were the mean lung dose (MLD), V₅ (percentage of lung volume that received a dose of 5 Gy or more)-V₅₀, and normal tissue complication probability (NTCP).

Results

Of the 100 patients, three suffered from symptomatic RP (symptom grade ≥2), but were relieved by supportive care. The risk of RP was not correlated with the treatment regimen. RP associated mostly with asymptomatic minimal pulmonary radiologic change or mild dry cough developed more frequently in the group with MLD ≥20.5 Gy or NTCP ≥23% than in the group with MLD <20.5 Gy and NTCP <23% (48.6% vs. 25.4%, p=0.018).

Conclusion

Dosimetric parameters of MLD and NTCP were correlated with the incidence of RP, but the clinical impact was minimal. We suggest that PWT is a safe technique for the treatment of IMN for BCS patients with low risk of symptomatic RP.

Correlation of conventional and conformal plan parameters for predicting radiation pneumonitis in patients treated with breast cancer

Purpose

The purpose of this study is to evaluate the correlation between the conventional plan parameters and dosimetric parameters obtained from conformal radiotherapy (RT) planning, and between these parameters and radiation pneumontitis (RP) incidence.

Methods

Clinical and dosimetric data of 122 patients that were treated with mastectomy and adjuvant 3D conformal RT (39% received 2-field RT [2-FRT], and in addition, 61% received 4-field RT [4-FRT]) were retrospectively analyzed. Central lung depth (CLD), maximum lung depth (MLD), and lung length were measured by the conventional plan. Lung dose-volume histograms (DVH) were created with conformal planning, and the lung volumes receiving 5 to 50 Gy (V_5Gy to V_50Gy) were calculated. Minimum (D_min), maximum (D_max), and mean doses (D_mean) for the ipsilateral lung and bilateral lungs were measured by DVH. Correlations between 3D dosimetric data and 2D radiographic parameters were analyzed.

Results

The conventional plan parameters did not significantly differ between 2-FRT and 4-FRT. The conformal plan D_min, D_max, and D_mean values were higher in 4-FRT versus 2-FRT. CLD and MLD were correlated with DVH parameter V_5Gy to V_45Gy values for ipsilateral, as well as bilateral lungs for 2-FRT. MLD and ipsilateral D_mean via 2-FRT planning had the strongest positive correlation (r=0.76, p<0.01). Moderate correlations existed between CLD and ipsilateral and bilateral lung V_5Gy-45Gy, and between MLD and bilateral lung V_5Gy-45Gy values in 2-FRT. Only four patients developed symptomatic RP, 4 with 4-FRT and one with 2-FRT.

Conclusion

The conformal plan parameters were strongly correlated with dose-volume parameters for breast 2-FRT. With only 4 cases of Grade 3 RP observed, our study is limited in its ability to provide definitive guidance, however assuming that CLD is an indicator for RP, V_20Gy could be used as a predictor for RP and for 2-FRT. A well-defined parameters are still required to predict RP in 4-FRT.

Reirradiation of relapsed brain tumors in children

AIM

The aim of this study was to evaluate toxicity and response to fractionated reirradiation (FR) of relapsed primary brain tumors in children.

BACKGROUND

The treatment options for recurrent brain tumors in children previously irradiated are limited. Reirradiation is performed with fear due to the cumulative late CNS toxicity and the lack of a significant chance of cure.

MATERIALS AND METHODS

Between 2008 and 2009, eight children with a median age of 14.5 years with a diagnosis of a recurrent brain tumor underwent reirradiation. Initially, all patients were treated with surgery, chemotherapy and radiotherapy. The median time to the first recurrence after the initial treatment was 19.5 months. Intervals between radiotherapy courses were in the range of 5-51 mos. All retreatments were carried out with 3D image-based conformal methods. The total prescription dose was 40 Gy in a fraction of 5 × 2 Gy/week. The total cumulative dose ranged from 65 to 95 Gy (median: 75 Gy). The median cumulative biologically effective dose was 144 Gy (range: 126-181 Gy).

RESULTS

The median overall survival and progression free survival measured from the beginning of reirradiation was 17.5 and 6.5 months, respectively. During the first evaluation, four patients showed a complete or partial response, two did not respond radiologically. Two children were progressive at the time of reirradiation. Among children with progression that occurred during the first year after reirradiation, only two progressed in the treatment area. The repeated irradiation was well tolerated by all patients. No late complications have been observed.

CONCLUSION

In the absence of other treatment possibilities, the fractionated reirradiation with highly conformal three-dimensional planning could be a therapeutic choice in case of recurrent brain tumors in children. The control of craniospinal dissemination remains to be the main problem.

Conventional fractionated versus late course accelerated hyperfractionated three-dimensional conformal radiotherapy for esophageal cancer: a randomized controlled trial

AIM: To compare the efficacy and safety of conventional fractionated (CF) versus late course accelerated hyperfractionated (LCAF) three-dimensional conformal radiotherapy (3D-CRT) for esophageal cancer.

METHODS: Ninety-eight patients with esophageal carcinoma were divided into two groups: 55 treated by CF-3D-CRT (a total dose of 60-68 Gy, 2 Gy/F, 5 fractions a week) and 48 by LCAF-3D-CRT (a total dose of 61-67 Gy, first by CF-3D-CRT to a dose of 40 Gy, followed by LCAF-3D-CRT: 1.5 Gy/F, 2 fractions a day, 21-27 Gy).

RESULTS: The 1-, 2-, and 3-year survival rates were 79.2%, 56.3% and 43.8% in the LCAF group, and 74%, 54% and 36% in the CF group, respectively. The 1-, 2-, and 3-year local control rates were 81.3%, 62.5% and 50% in the LCAF group, and 78%, 58% and 42% in the CF group, respectively. The incidence of radiation-induced esophagitis was significantly lower in the CF group than in the LCAF group (72% vs 93.8%, P = 0.008). However, the rate of radiation-induced pneumonitis showed no significant difference between the two groups (10% vs 6.25%, P = 0.498).

CONCLUSION: The 1-, 2- and 3-year local control rates and survival rates of patients with esophageal carcinoma treated by LCAF-3D-CRT are superior to those treated by CF-3D-CRT though the incidence of radiation-induced esophagitis is higher in the LCAF group than in the CF group.

Evaluation of dose coverage to target volume and normal tissue sparing in the adjuvant radiotherapy of gastric cancers: 3D-CRT compared with dynamic IMRT

Purpose:

To assess the potential advantage of intensity-modulated radiotherapy (IMRT) over 3D-conformal radiotherapy (3D-CRT) planning in postoperative adjuvant radiotherapy for patients with gastric carcinoma.

Methods and materials:

In a retrospective study, for plan comparison, dose distribution was recalculated in 15 patients treated with 3D-CRT on the contoured structures of same CT images using an IMRT technique. 3D-conformal plans with three fields and four-fields were compared with seven-field dynamic IMRT plans. The different plans were compared by analyzing the dose coverage of planning target volume using TV₉₅, D_mean, uniformity index, conformity index and homogeneity index parameters. To assess critical organ sparing, D_mean, D_max, dose to one-third and two-third volumes of the OARs and percentage of volumes receiving more than their tolerance doses were compared.

Results:

The average dose coverage values of PTV with 3F-CRT and 4F-CRT plans were comparable, where as IMRT plans achieved better target coverage(p<0.001) with higher conformity index value of 0.81±0.07 compared to both the 3D-CRT plans. The doses to the liver and bowel reduced significantly (p<0.001) with IMRT plans compared to other 3D-CRT plans. For all OARs the percentage of volumes receiving more than their tolerance doses were reduced with the IMRT plans.

Conclusion:

This study showed that a better target coverage and significant dose reduction to OARs could be achieved with the IMRT plans. The IMRT can be preferred with caution for organ motion. The authors are currently studying organ motion in the upper abdomen to use IMRT for patient treatment.

Treatment outcomes of three-dimensional conformal radiotherapy for stage III non-small cell lung cancer

PURPOSE

To evaluate the treatment outcomes of the three-dimensional conformal radiotherapy (3D-CRT), in conjunction with induction chemotherapy, for the treatment of stage III non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Between November 1998 and March 2003, 22 patients with histologically proven, clinical stage III NSCLC, treated with induction chemotherapy, followed by 3D-CRT, were retrospectively analyzed. There were 21 males (96%) and 1 female (4%), with a median age of 68.5 (range, 42 approximately 79). The clinical cancer stages were IIIA and IIIB in 41 and 59%, respectively. The histologies were squamous cell carcinoma, adenocarcinoma and others in 73, 18 and 9%, respectively. Twenty patients (91%) received induction chemotherapy before radiation therapy. The majority of the chemotherapy regimen consisted of cisplatin and gemcitabine. Radiation was delivered with conventional anteroposterior/posteroanterior fields for 36 Gy, and then 3D-CRT was performed. The total radiation dose was 70.2 Gy. The median follow-up period was 17 months (range, 4~59 months).

RESULTS

The median overall survival was 19 months. The two and four-year overall survival rates were 37.9 and 30.3%, respectively. The median progression-free survival was 21 months. The two and four-year progression-free survival rates were 42.1 and 21%, respectively. The prognostic factors for overall survival by a univariate analysis were age, histology and T stage (p<0.05). Acute radiation toxicities, as evaluated by the RTOG toxicity criteria, included two cases of grade 3 lung toxicity and one case of grade 2 esophagus toxicity.

CONCLUSION

The radiation dose could be increased without a significant increment in the acute toxicities when using 3D-CRT. It also seems to be a safe, well-tolerated and effective treatment modality for stage III NSCLC.

Preliminary Results of Paclitaxel, Cisplatin and Concurrent High-Dose Radiation Therapy for Locally Advanced Non-Small-Cell Lung Cancer

PURPOSE

To investigate the feasibility, toxicity and response rate, of concurrent chemoradiation therapy with paclitaxel/cisplatin in stage III locally advanced non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Between May 1999 and December 2000, 80 patients with stage III NSCLC were enrolled in a prospective protocol. Radiotherapy was given to a total dose of 70.2 Gy (daily fraction of 1.8 Gy for 5 days), over an 8 week period, on the gross tumor volume, combined with chemotherapy. The concurrent chemotherapy consisted of paclitaxel (40 mg/m2) and 20 mg/m2 cisplatin per week for 8 consecutive weeks. All patients received 3-D conformal radiotherapy using CT-simulated planning. Acute toxicities were evaluated by the RTOG scale. The median follow-up period was 16 months, ranging from 3 to 29 months.

RESULTS

Of the 80 patients, 71 received treatment per protocol, with minor variation of protocol delivery. The median age of the patients was 60 years. Karnofsky Performance status were 100 and 90 in 62 patients, and 80 and 70 in 9, respectively. Weight loss of less than 5% for 6 months was observed in 22 patients. The response to treatment was evaluated from the radiological findings. Complete and partial responses were observed in 8 and 51 patients, respectively. Ultimately, 82% of patients (included complete responses: 8 cases) obtained more than a partial response. Although, radiation induced esophagitis was the most common treatment related toxicity, occurring in 44 patients (69%), severe radiation esophagitis like, grade 3, was observed in only 3 patients, and the most acute toxicities had completely recovered 1 month following treatment. The overall 2-year actuarial and progression free survivals were 56 and 45%, respectively.

CONCLUSION

This combined modality has activity with manageable toxicity and 23 months in mean survival time in patients with stage III NSCLC. A longer follow up will be required to realise the expected higher survival of these results.