Impact of Lymph node Boost with External Beam Radiotherapy on Prognosis in Node-positive Carcinoma Cervix: A Retrospective study from a Tertiary Care Centre in South India
Dr. Sravana Kumari Chintam *1, Dr. Mohana Priya 1
*Correspondence to: Dr. Sravana Kumari Chintam, Department of Radiation Oncology, GSL Cancer Hospital, Rajahmundry, India.
Copyright
© 2026 Dr. Sravana Kumari Chintam is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 22 July 2026
Published: 01 August 2026
DOI: https://doi.org/10.5281/zenodo.21715284
Abstract
This retrospective institutional study evaluated the impact of pelvic lymph node (PLN) boost on prognostic factors like disease-free survival (DFS) & overall survival (OS) in patients with node-positive carcinoma cervix treated with definitive chemoradiation. A total of 153 patients with radiologically confirmed pelvic nodal involvement were included. All received external beam radiotherapy (EBRT) with concurrent weekly cisplatin followed by intracavitary brachytherapy. Among them, 44 patients received a boost to involved PLNs (total dose 60–66 Gy EQD2) using conformal techniques, while 109 patients did not receive any nodal boost. The median DFS was significantly higher in the boost group (39.5 months) compared to the non-boost group (18.4 months). However, the mean Overall Survival (OS) was 22.7 months in the boost arm and 29.9 months in the non-boost arm. Patients who received a nodal boost showed a trend towards improved local control and reduced nodal failure; it did not translate into an OS advantage in this cohort. These findings suggest that dose escalation to radiologically involved pelvic nodes may offer better disease control and support the inclusion of PLN boost in the treatment strategy for selected patients with node-positive cervical cancer.
Keywords: Carcinoma cervix, pelvic lymph node boost, node-positive, radiotherapy, disease-free survival, chemoradiation.
Introduction
Carcinoma cervix ranks second in incidence and mortality, with an estimated 127526 new cases and 79906 deaths, accounting for 8.7% of all female cancers deaths in India[1]. Concurrent chemoradiotherapy, followed by brachytherapy is the standard of care for locally advanced cervical cancer. However, involvement of lymph nodes is a well-established prognostic factor, influencing the outcomes including disease free and overall survival. Overall incidences of pelvic lymph node (PLN) and para aortic lymph node (PALN) in cervical cancer at presentation vary from ~35-50% and ~10-25% respectively[2],[3]. Nodal positivity is influenced by tumor size, depth of stromal invasion, lymph vascular space invasion (LVSI), histologic grade and type. FIGO 2018 staging has introduced stage IIIC1 (PLN) and IIIC2 (PALN), considering the prognostic weight of nodal involvement[4].
Standard pelvic radiation doses i.e. 45-50.4 Gy may control microscopic disease, while grossly involved nodes may require a dose escalation i.e. nodal boost to achieve better local control. Multiple studies have demonstrated that achieving a sufficient biological equivalent dose (BED) of more than or equal to 60 Gy EQD2 to involved nodes, especially radiologically significant or Positron Emission Tomography (PET) positive nodes as they often exhibit higher tumor burden and aggressive biology, correlates with better nodal control[5]. Furthermore, untreated or inadequately treated nodal disease often serves as a nidus for recurrence. Nodal failure contributes to both locoregional and systemic disease progression. This underlines the need for nodal boosting whereas the potential toxicities especially gastrointestinal and hematologic is a concern. However, a nodal boost using intensity modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) techniques allow focused dose escalation while sparing adjacent organs at risks (OARs)[6],[7].
There is no consensus on nodal boost as there is a variability in institutional practices, with some centers opting for selective boosting based on size, PET avidity, response to therapy while some centers not due to toxicity. So, there is a clear need for more robust data to evaluate whether nodal boosts provide a meaningful survival benefit without compromising safety. Our retrospective study aims to analyze the impact of nodal boost on disease free survival in a cohort of node positive cervical carcinoma patients treated with chemo radiation.
Methods and Material
A retrospective observational study included consecutive 419 patients with histologic proven carcinoma cervix treated with definitive or adjuvant chemoradiotherapy at our institute between April 2020 and March 2024. Patients were staged according to FIGO 2018 staging based on clinical, radiological (MRI pelvis or PET-CT), and histopathological findings. Lymph nodes >10 mm in short axis diameter (SAD) were considered as enlarged. Suspicious lymph nodes like lymph nodes <10 mm with round or irregular shape on Computed Tomography (CT) or Magnetic Resonance imaging (MRI) with or without necrosis and PET avid nodes with maximum standardized uptake value (SUVmax) > 4 were also considered as involved lymph nodes.
Radiotherapy
All patients underwent CT simulation in supine position with hands above the head or placed on the chest depending on comfort and immobilized with a customized pelvic thermoplastic mask to ensure reproducibility. Patients were instructed to maintain a comfortably full bladder and empty rectum to minimize organ motion. A planning CT scan was acquired with intravenous contrast. Target delineation includes Clinical Target Volume of primary (CTV_p), which consists of Gross tumor volume (GTV), uterus, parametrium and 2cm of uninvolved vagina and bilateral common iliac, external iliac, internal iliac lymph nodal regions, presacral and obturator lymph nodal region were included in elective CTV_n i.e. up to L4 - L5 interspace. Inguinal lymph nodal region included when there was an involvement of lower one third of vagina and enlarged nodes in the inguinal region. Extended field radiotherapy was administered to the patients with enlarged PALN i.e. up to T11-T12 vertebral junction. For lymph node boost, a 5 mm margin was given to GTV_n to generate CTV_n boost. Planning target volume was generated by giving a margin of 5 mm margin to CTVs. Patients were planned either with 3D Conformal Radiotherapy (3DCRT) using four-field box technique or IMRT or VMAT with image guidance (IGRT), depending on disease extent and institutional resources.
The dose of External Beam Radiotherapy (EBRT) ranged from 45 - 50.4 Gy at 1.8 Gy per fractions, delivered 5 fractions per week. Additional boost to the enlarged lymph nodes with dose ranging from 6 - 9 Gy was delivered. Plan evaluation was performed to ensure the prescribed dose adequately covered the PTV while respecting dose constraints to OARs as per institutional protocol.
Brachytherapy
Following EBRT, patients were evaluated for intracavitary brachytherapy (ICRT). ICRT was delivered using a standard uterine tandem and ovoids or vaginal cylinder based on individual patient anatomy and status of disease extent. A dose of 6-7 Gy for 3-4 fractions was prescribed to point A, OARs (Bladder, Rectum, Sigmoid) doses were evaluated and noted for each fraction.
Chemotherapy
Concurrent chemotherapy regimen was selected based on patient tolerance, performance status, renal function and hematologic parameters. Patients with good renal function received weekly cisplatin at a dose of 40mg/m2 or weekly carboplatin AUC 2. Patients with poor tolerability, comorbidities and situations (postoperative case) where chemotherapy was not indicated, were not received chemotherapy.
Follow-up protocol
All patients were advised regular follow-up after completion of radiotherapy. All patients were instructed to visit at 6 weeks post treatment for first follow-up, followed by every 3 months for the first 2 years, every 6 months for the next 3 years, and annually thereafter. Clinical evaluation with detailed history and pelvic examination done in each visit. Imaging with ultrasound (USG), chest X ray, or CT/MRI was performed as clinically indicated, based on the affordability of the patients.
Results
A total of 419 patients with carcinoma cervix treated with definitive chemoradiation between April 2020 and March 2024 were included. The mean age at presentation was 52.2years (26 - 84 years), with the majority (66.5%) falling within the 41 - 60 years age group. Squamous cell carcinoma was the most common histology, seen in 94% of patients, followed by adenocarcinoma in 5.2%. According to FIGO staging (2018), Stage IIIC1 was the most frequent, observed in 123 patients (29.4%), followed by Stage IIB in 113 patients (27%). Out of the total 419 patients, 153 patients (36.5%) were found to have PLN involvement, among these, 16 were postoperative cases. Extended field radiotherapy was given to 16 (3.8%) who had PALN involvement.
All patients received whole pelvis radiotherapy to a dose of 50Gy. Of the evaluable cohort, 44 patients (32.1%) received a nodal boost, while 93 patients (67.9%) did not. The mean short-axis diameter of the involved lymph node was 13.5 mm, with the largest measuring up to 40 mm. At presentation, a single enlarged lymph node was identified in 57 patients, 2-3 nodes in 54 patients, and multiple (>3) in 26 patients. Obturator group of lymph nodes was the most commonly involved site, followed by the internal and external iliac nodes. A boost dose of 6 Gy was delivered in 39 patients, while 4 patients received a dose ranging from 9-10 Gy. Boost was delivered using IMRT-based techniques, sequentially in 18 patients and simultaneously integrated with primary treatment in 26 patients Fig (1-2).
The median follow-up period was 26 months. The Disease-Free Survival (DFS) was significantly better in patients who received a nodal boost, with a median DFS of 39.5 months compared to 18.4 months in those who did not receive a boost. However, the mean Overall Survival (OS) was 22.7 months in the boost arm and 29.9 months in the non-boost arm. Patients who received a nodal boost showed a trend towards improved local control and reduced nodal failure; it did not translate into an OS advantage in this cohort. However, this may not reflect true prognostic difference, as a larger proportion of patients in the non-boost group were treated in earlier years (2021-2022), leading to longer follow up data and survival capture. Although to get statistical significance, prospective studies with larger sample size may help.
Discussion
Pelvic lymph node involvement is a well-established adverse prognostic factor in carcinoma cervix, influencing both DFS and OS. This study aimed to find the impact of delivering an additional dose to radiologically positive pelvic lymph nodes that could improve oncologic outcomes in node positive cervical cancer patients treated with definitive chemoradiation.
Among the 153 node positive patients analyzed, 44 patients received a nodal boost and these patients showed significantly improved DFS of 39.4 months compared to 18.4 months in the non-boost group. This suggests that delivering a higher dose to radiologically positive nodes may contribute to better regional control, consistent with evidence from prior studies. A study by Richa Tiwari et al. (2021) investigated the impact of nodal boost irradiation in patients with node-positive locally advanced carcinoma cervix undergoing standard chemoradiation and MRI-based brachytherapy demonstrated that delivering a boost to grossly involved lymph nodes resulted in improved pelvic control without a significant increase in toxicity. However, it also emphasized the persistent challenge of systemic failures, which continued to limit the overall survival benefit [8].
A study by Tanderup et al. emphasized dose-adapted strategies in advanced nodal disease to reduce the risk of recurrence [9].
However, the OS in our cohort did not mirror this benefit. The non-boost group had an OS of 29.9 months, while the boost group had 22.7 months. This discrepancy may be explained by follow-up bias, as many patients in the non-boost arm were treated earlier (in 2021–2022), thus having a longer follow-up duration. Additionally, the boost group likely had more aggressive disease characteristics, such as larger nodes (mean short-axis 13.5 mm) and multiple nodal involvements, which may have affected OS outcomes.
Most commonly involved nodal sites were the obturator and internal iliac nodes, which align with the typical lymphatic spread pattern in carcinoma cervix. Accurate nodal assessment is fundamental. The well-cited meta-analysis by Choi et al. demonstrated that imaging modalities (CT, MRI, PET-CT) have variable sensitivity and specificity for detecting nodal metastases in cervical cancer, underscoring the need for boost decisions to be informed by tumor size, PET avidity, and radiological characteristics[10]. Most of our patients had nodes averaging 13.5 mm, emphasizing the appropriateness of boost in this subgroup.
Boost doses ranged from 6 to 10 Gy, delivered via sequential or simultaneous integrated boost (SIB) methods, using advanced techniques such as IMRT/VMAT. Dosimetric studies, including those by B Rai et al. and Yidi yuan et al., support the use of IMRT/VMAT in cervical cancer for improved organ-at-risk (OAR) sparing and better dose conformity [11,12].
Conclusion
This retrospective analysis highlights that pelvic lymph node boost in node-positive carcinoma cervix patients receiving definitive chemoradiation is associated with significantly improved disease-free survival. Although no corresponding benefit was observed in overall survival, this discrepancy may be due to differences in follow-up duration and disease characteristics. These findings emphasize the potential role of tailored radiation strategies such as nodal boosts - in enhancing locoregional control. However, further prospective, randomized studies are warranted to validate the survival benefit and establish standardized boost protocols.
Limitations
Declaration of patient consent
Consent forms obtained from all patients appropriately in which they have given their consent for clinical information to be reported in the study.
Funding: Nil.
Conflicts of interest
There are no conflicts of interest.
References