Dataset Information

Incidental Dose to Pelvic Nodes in Bladder-Only Radiotherapy: Is It Clinically Relevant?

ABSTRACT:

Background and purpose

Although there is a strong biological rationale to electively treat the pelvic nodes during bladder preservation, its clinical benefit is uncertain. This may be explained by the incidental dose received by the nodal regions when treating the bladder alone. This study was conducted to investigate the doses received by the different pelvic nodal regions when the bladder alone is treated by standard conformal radiotherapy.

Methods and materials

The computed tomography data sets of 20 patients with node-negative muscle-invasive bladder cancer treated in a bladder preservation protocol were studied. Patients were originally treated with conformal radiotherapy to the bladder alone. Replanning was done with additional delineation of the pelvic nodal regions namely common iliac (upper and lower), presacral, internal iliac, obturator, and external iliac. Dose volume parameters such as Dmean, Dmax, D100%, D66%, D33%, V40, and V50 to each of the nodal regions were estimated for all patients.

Results

The obturator nodes received the highest dose among all nodal regions. The mean dose received by obturator, external iliac, and internal iliac regions was 59, 45, and 36 Gy, respectively. The dose received by these 3 regions in the full bladder state was 63, 52, and 47 Gy, respectively. The dose received by all other pelvic nodal regions was low and not clinically relevant.

Conclusion

The incidental dose received by obturator and external iliac nodes is clinically significant in bladder-only radiation, possibly enough to influence micrometastatic disease. This may be a reason for the lack of clear benefit seen with nodal irradiation in bladder cancer. Advances in Knowledge: This study highlights that the incidental dose received by obturator and external iliac nodes is clinically significant in bladder-only radiation. The obturator nodes received the highest dose among all nodal regions with mean dose of 59 Gy.

SUBMITTER: Lewis S

PROVIDER: S-EPMC5616055 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Publications

Incidental Dose to Pelvic Nodes in Bladder-Only Radiotherapy: Is It Clinically Relevant?

Lewis Shirley S Murthy Vedang V Mahantshetty Umesh U Shrivastava Shyam Kishore SK

Technology in cancer research & treatment 20170207 3

<h4>Background and purpose</h4>Although there is a strong biological rationale to electively treat the pelvic nodes during bladder preservation, its clinical benefit is uncertain. This may be explained by the incidental dose received by the nodal regions when treating the bladder alone. This study was conducted to investigate the doses received by the different pelvic nodal regions when the bladder alone is treated by standard conformal radiotherapy.<h4>Methods and materials</h4>The computed tom ...[more]

PMID: 28168933

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Project description:ObjectivesPelvic lymph nodal regions receive an incidental dose from conformal treatment of the prostate. This study was conducted to investigate the doses received by the different pelvic nodal regions with varying techniques used for prostate radiotherapy.Methods and materialsTwenty patients of high-risk node-negative prostate cancer treated with intensity-modulated radiotherapy to the prostate alone were studied. Replanning was done for intensity-modulated radiotherapy, 3-dimensional conformal treatment, and 2-dimensional conventional radiotherapy with additional delineation of the pelvic nodal regions, namely, common iliac (upper and lower), presacral, internal iliac, obturator, and external iliac. Dose-volume parameters such as Dmean, D100%, D66%, D33%, V40, and V50 to each of the nodal regions were estimated for all patients.ResultsThe obturator nodes received the highest dose among all nodal regions. The mean dose received by obturator nodal region was 44, 29, and 22 Gy from 2-dimensional conventional radiotherapy, 3-dimensional conformal treatment, and intensity-modulated radiotherapy, respectively. The mean dose was significantly higher when compared between 2-dimensional conventional radiotherapy and 3-dimensional conformal treatment ( P < .001), 2-dimensional conventional radiotherapy and intensity-modulated radiotherapy ( P < .001), and 3-dimensional conformal treatment and intensity-modulated radiotherapy ( P < .001). The D33% of the obturator region was 64, 39, and 37 Gy from 2-dimensional conventional radiotherapy, 3-dimensional conformal treatment, and intensity-modulated radiotherapy, respectively. The dose received by all other pelvic nodal regions was low and not clinically relevant.ConclusionThe incidental dose received by obturator regions is significant especially with 2-dimensional conventional radiotherapy and 3-dimensional conformal treatment techniques as used in the trials studying elective pelvic nodal irradiation. However, with intensity-modulated radiotherapy, this dose is lower, making elective pelvic irradiation more relevant. Advances in Knowledge: This study highlights that incidental dose received by obturator regions is significant especially with 2-dimensional conventional radiotherapy and 3-dimensional conformal treatment techniques.

Project description:BackgroundAbdominal/pelvic lymph node (LN) oligometastasis, a pattern of treatment failure, is observed occasionally, and radiotherapy may work as salvage therapy. The optimal prescription dose, however, is yet to be determined. This study assessed the efficacy of high-dose radiotherapy.MethodsThe medical records of 113 patients at 4 institutes were retrospectively analysed who had 1 to 5 abdominal/pelvic LN oligometastases and were treated with definitive radiotherapy between 2008 and 2018. The exclusion criteria included non-epithelial tumours, uncontrolled primary lesions, palliative intent, and re-irradiation. The prescription dose was evaluated by using the equivalent dose in 2?Gy fractions (EQD2). Patients receiving EQD2???60?Gy were placed into the high-dose group, and the remaining others the low-dose group. Kaplan-Meier analyses were performed to evaluate overall survival (OS), local control (LC), and progression-free survival (PFS). Univariate log-rank and multivariate Cox proportional hazards model analyses were performed to explore predictive factors. Adverse events were compared between the high-dose and low-dose groups.ResultsThe primary tumour sites included the colorectum (n?=?28), uterine cervix (n?=?27), endometrium (n?=?15), and ovaries (n?=?10). The rate of 2-year OS was 63.1%, that of LC 59.7%, and that of PFS 19.4%. On multivariate analyses, OS were significantly associated with solitary oligometastasis (hazard ratio [HR]: 0.48, p?=?0.02), LC with high-dose radiotherapy (HR: 0.93, p?<?0.001), and PFS with long disease-free interval (HR: 0.59, p?=?0.01). Whereas high-dose radiotherapy did not significantly improve 2-year OS in the entire cohort (74.8% in the high-dose vs. 52.7% in the low-dose; p?=?0.08), it did in the subgroup of solitary oligometastasis (88.8% in the high-dose vs. 56.3% in the low-dose; p?=?0.009). As for Late grade???3 adverse event, ileus was observed in 7 patients (6%) and gastrointestinal bleeding in 4 (4%). No significant association between the irradiation dose and adverse event incidence was found.ConclusionsAs salvage therapy, high-dose radiotherapy was recommendable for oligometastasis in the abdominal/pelvic LNs. For solitary oligometastasis, LC and OS were significantly better in the high-dose group.

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Project description:PURPOSE/OBJECTIVE(S):Along with breast-conserving surgery (BCS), adjuvant radiotherapy (RT) of patients with early breast cancer plays a crucial role in the oncologic treatment concept. Conventionally, irradiation is carried out with the aid of tangentially arranged fields. However, more modern and more complex radiation techniques such as IMRT (intensity-modulated radio therapy) are used more frequently, as they improve dose conformity and homogeneity and, in some cases, achieve better protection of adjacent risk factors. The use of this technique has implications for the incidental- and thus unintended- irradiation of adjacent loco regional lymph drainage in axillary lymph node levels I-III and internal mammary lymph nodes (IMLNs). A comparison of a homogeneous "real-life" patient collective, treated with helical tomotherapy (TT), patients treated with 3D conformal RT conventional tangentially arranged fields (3DCRT) and deep inspiration breath hold (3DCRT-DIBH), was conducted. MATERIALS/METHODS:This study included 90 treatment plans after BCS, irradiated in our clinic from January 2012 to August 2016 with TT (n?=?30) and 3D-CRT (n?=?30), 3DCRT DIBH (n?=?30). PTVs were contoured at different time points by different radiation oncologists (>?7). TT was performed with a total dose of 50.4?Gy and a single dose of 1.8?Gy with a simultaneous integrated boost (SIB) to the tumor cavity (TT group). Patients irradiated with 3DCRT/3DCRT DIBH received 50?Gy à 2?Gy and a sequential boost. Contouring of lymph drainage routes was performed retrospectively according to RTOG guidelines. RESULTS:Average doses (DMean) in axillary lymph node Level I/Level II/Level III were 31.6?Gy/8.43?Gy/2.38?Gy for TT, 24.0?Gy/11.2?Gy/3.97?Gy for 3DCRT and 24.7?Gy/13.3?Gy/5.59?Gy for 3DCRT-DIBH patients. Internal mammary lymph nodes (IMLNs) Dmean were 27.8?Gy (TT), 13.5?Gy (3DCRT), and 18.7?Gy (3DCRT-DIBH). Comparing TT to 3DCRT-DIBH dose varied significantly in all axillary lymph node levels and the IMLNs. Comparing TT to 3DCRT significant dose difference in Level I and IMLNs was observed. CONCLUSION:Dose applied to locoregional lymph drainage pathways varies comparing tomotherapy plans to conventional tangentially arranged fields. Studies are warranted whether dose variations influence loco-regional spread and must have implications for target volume definition guidelines.

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Dataset Information

Incidental Dose to Pelvic Nodes in Bladder-Only Radiotherapy: Is It Clinically Relevant?

Background and purpose

Methods and materials

Results

Conclusion

Publications

Incidental Dose to Pelvic Nodes in Bladder-Only Radiotherapy: Is It Clinically Relevant?

Similar Datasets

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