Indications for adjuvant radiotherapy treatment after surgery and novel modalities for treatment

A prior-information-based automatic segmentation method for the clinical target volume in adaptive radiotherapy of cervical cancer

OBJECTIVE

Adaptive planning to accommodate anatomic changes during treatment often requires repeated segmentation. In this study, prior patient-specific data was integrateda into a registration-guided multi-channel multi-path (Rg-MCMP) segmentation framework to improve the accuracy of repeated clinical target volume (CTV) segmentation.

METHODS

This study was based on CT image datasets for a total of 90 cervical cancer patients who received two courses of radiotherapy. A total of 15 patients were selected randomly as the test set. In the Rg-MCMP segmentation framework, the first-course CT images (CT1) were registered to second-course CT images (CT2) to yield aligned CT images (aCT1), and the CTV in the first course (CTV1) was propagated to yield aligned CTV contours (aCTV1). Then, aCT1, aCTV1, and CT2 were combined as the inputs for 3D U-Net consisting of a channel-based multi-path feature extraction network. The performance of the Rg-MCMP segmentation framework was evaluated and compared with the single-channel single-path model (SCSP), the standalone registration methods, and the registration-guided multi-channel single-path (Rg-MCSP) model. The Dice similarity coefficient (DSC), 95% Hausdorff distance (HD95), and average surface distance (ASD) were used as the metrics.

RESULTS

The average DSC of CTV for the deformable image DIR-MCMP model was found to be 0.892, greater than that of the standalone DIR (0.856), SCSP (0.837), and DIR-MCSP (0.877), which were improvements of 4.2%, 6.6%, and 1.7%, respectively. Similarly, the rigid body DIR-MCMP model yielded an average DSC of 0.875, which exceeded standalone RB (0.787), SCSP (0.837), and registration-guided multi-channel single-path (0.848), which were improvements of 11.2%, 4.5%, and 3.2%, respectively. These improvements in DSC were statistically significant (p < 0.05).

CONCLUSION

The proposed Rg-MCMP framework achieved excellent accuracy in CTV segmentation as part of the adaptive radiotherapy workflow.

Dihydroouabain, a novel radiosensitizer for cervical cancer identified by automated high-throughput screening

BACKGROUND AND PURPOSE

Radiotherapy plays a crucial role in the treatment of cervical cancer, but existing radiosensitizers have limited efficacy in clinical applications. The aims of this study were to establish and verify an efficient method for identifying new radiosensitizers, to use this to identify candidate radiosensitizers for cervical cancer, and to investigate the specific mechanisms of these when used in combination with radiotherapy.

MATERIALS AND METHODS

An automated platform for identifying radiosensitizers for cervical cancer was created based on high-throughput screening technology. The radiosensitizing effects of candidate compounds from the LOPAC1280 chemical library were evaluated in radiosensitive and radioresistant cervical cancer cells using a clonogenic survival assay, with cell cycle analyses, and western blot analyses performed for both cell lines.

RESULTS

The automated high-throughput screening approach identified four hit compounds. One of the most potent candidates was dihydroouabain (DHO), an inhibitor of Na⁺/K⁺-ATPase that has not previously been classified as a radiosensitizer. DHO significantly enhanced radiosensitivity in cervical cancer cells. It also abrogated radiation-induced S phase arrest in cervical cancer cells. Combination treatment significantly caused the inhibition of Chk1 and increased DNA double-strand breaks (DSB).

CONCLUSIONS

DHO is a novel radiosensitizer for the treatment of cervical cancer. The automated high-throughput screening platform developed in this study proved to be powerful and effective, with the potential to be widely used in the future identification of radiosensitizers.

Extended field intensity-modulated radiotherapy plus concurrent nedaplatin treatment in cervical cancer

The present study assessed the efficacy and toxicity of definitive extended-field intensity-modulated radiotherapy (EF-IMRT) plus concurrent chemotherapy in cervical cancer. A total of 48 patients with cervical cancer received the planning target volume between 39.6 and 50.4 Gy in 1.8-2.0 Gy daily fractions, while the enlarged pelvic and/or para-aortic nodes were treated with a total dose of 55-60 Gy in 2.0-2.4 Gy daily fractions using simultaneous integrated boost-IMRT. All patients underwent high dose-rate brachytherapy. Concurrent to EF-IMRT, nedaplatin was administered weekly at a median dose of 30 mg/m² (range, 25-40 mg/m²) for 5 weeks with a total of 150 mg/m². Of the 48 patients, 46 patients exhibited initial complete responses and 2 patients had partial responses, with a response rate of 100%. After 4-24 months of treatment, 12 patients (27.08%) had local and/or distant failure and 39 patients (81.25%) were alive at the last follow-up. The 12-month overall survival (OS) and disease-free survival (DFS) were 87.5 and 75.8%, respectively, while the 24-month OS and DFS were 69.7 and 49.7%, respectively. Grade ≥3 acute neutropenia and thrombcytopenia occurred in 20 (41.7%) and 4 (8.3%) patients, respectively, while 2 patients (4.2%) developed grade ≥3 diarrhea and 2 (4.2%) had grade ≥3 late toxicities. However, no patients exhibited grade ≥3 vomiting. Thus, concurrent nedaplatin chemotherapy with definitive EF-IMRT was effective and relatively safe for treating patients with cervical cancer. Furthermore, EF-IMRT was able to deliver ≤60 Gy to enlarged para-aortic and/or pelvic nodes using simultaneous integrated boost without increased acute and late gastrointestinal toxicity.

Impact of various treatment modalities on the outcome of stage IB1-IIA cervical adenocarcinoma

OBJECTIVE

To evaluate the outcomes of patients with stage IB1-IIA cervical adenocarcinoma treated by various modalities in order to formulate a better treatment strategy.

METHODS

The impact of various treatment modalities on the prognosis of 258 patients with stage IB1-IIA cervical adenocarcinoma was investigated. The therapeutic modalities included radical surgery (n=174); radical surgery followed by adjuvant radiation therapy (RT), such as RT alone or concurrent chemo-radiotherapy (CCRT) (n=46); or primary RT or CCRT (n=38).

RESULTS

As compared with patients in the surgery-only group, patients with 1 postoperative major risk who underwent surgery followed by RT or CCRT had a significantly higher likelihood of disease relapse (2.3-fold, P=0.041) and disease-related death (2.9-fold, P=0.014). The likelihood of recurrence (P=0.32) and death (P=0.58) did not differ between patients who underwent adjuvant RT or CCRT for 1 major risk factor and those who underwent primary RT or CCRT. By contrast, patients with more than 1 major risk factor had a higher likelihood of disease recurrence (2.9-fold, P=0.037) and disease-related death (3.4-fold, P=0.051) than those who underwent primary RT or CCRT.

CONCLUSION

Radical surgery is recommended for patients with stage IB1-IIA cervical adenocarcinomas without contraindications. Those with more than 1 postoperative pathologic risk factor had the worst prognosis despite adjuvant RT or CCRT.

Intensity-modulated radiation therapy versus para-aortic field radiotherapy to treat para-aortic lymph node metastasis in cervical cancer: prospective study

AIM

To compare dosimetry, efficacy, and toxicity of intensity-modulated radiation therapy (IMRT) with para-aortic field radiotherapy in patients with para-aortic lymph node (PALN) metastasis of cervical cancer.

METHODS

This prospective study examined 60 patients with cervical cancer with PALN metastasis who underwent whole-pelvis radiotherapy followed by brachytherapy between November 1, 2004 and May 31, 2008. After 3 cycles of chemotherapy, patients were serially allocated into two groups and treated with IMRT or para-aortic field RT at doses of 58-68 Gy and 45-50 Gy, respectively. Treatment response was evaluated and toxicities were assessed. Patients in the IMRT group were treated with both para-aortic field RT and IMRT in order to compare the exposure dose of organs at risk.

RESULTS

In the IMRT group, the mean dose delivered to the planning target volume was 67.5 Gy. At least 99% of the gross tumor volume received effective coverage and radical dose (median, 63.5 Gy; range, 54.5-66) during treatment. IMRT plans yielded better dose conformity to the target and better sparing of the spinal cord and small intestine than para-aortic field RT. The IMRT patients experienced less acute and chronic toxicities. The IMRT group also had higher 2- and 3-year survival rates than the para-aortic RT group (2-year, 58.8% vs 25.0%, P = 0.019; 3-year, 36.4% vs 15.6%, P = 0.016). However, no significant difference was found in 1-year survival (67.7% vs 51.3%, P =0.201). The median survival in the IMRT group was 25 months (range, 3 to 37 months). The actuarial overall survival, disease-free survival, and locoregional control rates at 2 years were 67%, 77%, and 88%, respectively, in the IMRT group.

CONCLUSIONS

IMRT provides better clinical outcomes than para-aortic field radiotherapy in patients with PALN metastasis. However, cervical local and distal recurrence remain a problem. Long-term follow-up and studies involving more patients are needed to confirm our results.

Value of PET-CT in avoiding multimodality therapy in operable cervical cancer

BACKGROUND

Posttreatment morbidity of multimodality therapy is substantially higher than either radical surgery or chemoradiation alone. Preoperative prediction of positive nodes limits optimal selection of the primary treatment modality. Computed tomography (CT) and magnetic resonance imaging have been tried for nodal assessment with modest results. Positron emission tomography (PET) combined with CT seems to be promising in this regard. This clinicopathologic study assesses the value of PET-CT in predicting nodal metastasis and avoiding multimodality therapy.

MATERIALS AND METHODS

Eighty patients with clinically operable cervical cancer underwent PET-CT during the preoperative evaluation followed by radical hysterectomy. Adjuvant chemoradiation was administered when indicated by histopathologic findings. The histopathologic finding of the pelvic nodes was correlated with the PET-CT findings for nodal metastasis. The chi2 test was used as the test of significance in the statistical analysis.

OBSERVATIONS

Of 62 patients found PET-CT negative for nodal disease, 52 were true negative, whereas 10 were false negative on histopathologic examination. On the other hand, 14 of 18 patients found PET-CT positive for nodal disease were true positives. Specificity, sensitivity, positive predictive value, and negative predictive value of PET-CT in nodal assessment were found to be 92.8, 58.33, 77.7, and 83.8, respectively. Twenty-four patients (30%) with pelvic nodes positive for disease on histopathologic examination were administered adjuvant chemoradiation. Had we operated only on those patients who were PET-CT negative for nodal disease, 10 of 62 patients would have required adjuvant chemoradiation for positive nodes. Eighteen patients found PET-CT positive for nodal disease would be treated with primary chemoradiation. Inclusion of PET-CT in the decision-making process for primary surgery versus primary chemoradiation would allow 87.5% patients to receive a single modality of treatment (65%, only surgery; 22.5%, only chemoradiation) and the proportion of patients requiring multimodality treatment would reduce significantly from 30% to 12.5% (P < 0.01).

CONCLUSION

Positron emission tomography combined with CT in the evaluation of operable cervical cancer can help in the optimal selection of patients for surgery such that multimodality treatment with its attendant increase in morbidity is avoided.

Effect of intensity-modulated pelvic radiotherapy on second cancer risk in the postoperative treatment of endometrial and cervical cancer

PURPOSE

To estimate and compare intensity-modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3DCRT) in terms of second cancer risk (SCR) for postoperative treatment of endometrial and cervical cancer.

METHODS AND MATERIALS

To estimate SCR, the organ equivalent dose concept with a linear-exponential, a plateau, and a linear dose-response model was applied to dose distributions, calculated in a planning computed tomography scan of a 68-year-old woman. Three plans were computed: four-field 18-MV 3DCRT and nine-field IMRT with 6- and 18-MV photons. SCR was estimated as a function of target dose (50.4 Gy/28 fractions) in organs of interest according to the International Commission on Radiological Protection.

RESULTS

Cumulative SCR relative to 3DCRT was +6% (3% for a plateau model, -4% for a linear model) for 6-MV IMRT and +26% (25%, 4%) for the 18-MV IMRT plan. For an organ within the primary beam, SCR was +12% (0%, -12%) for 6-MV and +5% (-2%, -7%) for 18-MV IMRT. 18-MV IMRT increased SCR 6-7 times for organs away from the primary beam relative to 3DCRT and 6-MV IMRT. Skin SCR increased by 22-37% for 6-MV and 50-69% for 18-MV IMRT inasmuch as a larger volume of skin was exposed.

CONCLUSION

Cancer risk after IMRT for cervical and endometrial cancer is dependent on treatment energy. 6-MV pelvic IMRT represents a safe alternative with respect to SCR relative to 3DCRT, independently of the dose-response model. 18-MV IMRT produces second neutrons that modestly increase the SCR.