Radiation-Induced Lymphopenia Predicts Poorer Prognosis in Patients With Breast Cancer: A Post Hoc Analysis of a Randomized Controlled Trial of Postmastectomy Hypofractionated Radiation Therapy

Interpretable deep learning insights: Unveiling the role of 1 Gy volume on lymphopenia after radiotherapy in breast cancer

BACKGROUND

Lymphopenia is known for its significance on poor survivals in breast cancer patients. Considering full dosimetric data, this study aimed to develop and validate predictive models for lymphopenia after radiotherapy (RT) in breast cancer.

MATERIAL AND METHODS

Patients with breast cancer treated with adjuvant RT were eligible in this multicenter study. The study endpoint was lympopenia, defined as the reduction in absolute lymphocytes and graded lymphopenia after RT. The dose-volume histogram (DVH) data of related critical structures and clinical factors were taken into account for the development of dense neural network (DNN) predictive models. The developed DNN models were validated using external patient cohorts.

RESULTS

A total of 918 consecutive patients with invasive breast cancer enrolled. The training, testing, and external validating datasets consisted of 589, 203, and 126 patients, respectively. Treatment volumes at nearly all dose levels of the DVH were significant predictors for lymphopenia following RT, including volumes at very low-dose 1 Gy (V1) of organs at risk (OARs) including lung, heart and body, especially ipsilateral-lung V1. A final DNN model, combining full DVH dosimetric parameters of OARs and three key clinical factors, achieved a predictive accuracy of 75 % or higher.

CONCLUSION

This study demonstrated and externally validated the significance of full dosimetric data, particularly the volume of low dose at as low as 1 Gy of critical structures on lymphopenia after radiation in patients with breast cancer. The significance of V1 deserves special attention, as modern VMAT RT technology often has a relatively high value of this parameter. Further study is warranted for RT plan optimization.

Lymphopenia after palliative radiotherapy for vertebral metastases

Lymphopenia is a well-known side effect of radiotherapy and has been shown to have a negative impact on patient outcomes. However, the extent of lymphopenia caused by palliative radiotherapy and its effect on patient prognosis has not been clarified. The aim of this study was to determine the incidence and severity of lymphopenia after palliative radiotherapy for vertebral metastases and to determine their effects on patients' survival outcomes. We conducted a retrospective analysis for patients who underwent palliative radiotherapy for vertebral metastases and could be followed up for 12 weeks. Lymphocyte counts were documented at baseline and throughout the 12-week period following the start of radiotherapy and their medians and interquartile ranges (IQRs) were recorded. Exploratory analyses were performed to identify predictive factors for lymphopenia and its impact on overall survival (OS). A total of 282 cases that met the inclusion criteria were analyzed. The median baseline lymphocyte count was 1.26 × 103/μl (IQR: 0.89-1.72 × 103/μl). Peak lymphopenia occurred at a median of 26 days (IQR: 15-45 days) with a median nadir of 0.52 × 103/μl (IQR: 0.31-0.81 × 103/μl). Long-term analysis of patients surviving for 1 year showed that lymphopenia persisted at 1 year after radiotherapy. The main irradiation site, radiation field length and pretreatment lymphocyte count were significantly related to grade 3 or higher lymphopenia. Lymphopenia was identified as a significant predictor of OS by multivariate Cox regression analysis. This study demonstrated the incidence of lymphopenia after palliative radiotherapy for vertebral metastases and its effect on patients' OS.

Prognostic value of lymphocytes in patients with breast cancer receiving radiotherapy after breast-conserving surgery: A post hoc analysis of a phase III randomized trial

PURPOSE

To evaluate the prognostic value of peripheral lymphocyte count (PLC) in the breast cancer patients after breast-conserving surgery (BCS) with radiotherapy (RT).

METHODS AND MATERIALS

This post hoc analysis was performed using data of 628 patients from a phase III, randomized controlled trial comparing hypofractionated RT (HFRT) with conventional fractionated RT (CFRT) after BCS. PLCs were obtained before, during, and after RT until the 1-year follow-up. The optimal cut-off PLCs were determined using the maxstat package in R. Survival rates were estimated using the Kaplan-Meier method and compared with the log-rank test.

RESULTS

A total of 275 (46.1 %) patients developed lymphopenia during RT, among them, 17 (2.8 %) had grade 3 lymphopenia and no one developed grade 4 lymphopenia. With a median follow-up of 110.8 months, patients with pre-RT PLCs of < 1.77 × 109/L had a significantly lower 10-year breast cancer-specific survival (BCSS) rate (P = 0.013) and overall survival (OS) rate (P = 0.026). Patients with a nadir PLC of < 1.35 × 109/L had a significantly poorer 10-year OS rate (P = 0.048). Multivariate analysis showed that a pre-RT PLC of < 1.77 × 109/L was an independent factor influencing BCSS and OS, while the effect of the nadir PLC did not remain significant. Neither PLC nor lymphopenia recovery at post-RT 1, 3, and 6 months and 1 year was associated with survival.

CONCLUSIONS

Radiation-induced lymphopenia in patients with breast cancer after BCS tends to be mild. The lower pre-RT PLC predicted poorer survival.

Translational Frontiers and Clinical Opportunities of Immunologically Fitted Radiotherapy

Ionizing radiation can have a wide range of impacts on tumor-immune interactions, which are being studied with the greatest interest and at an accelerating pace by the medical community. Despite its undeniable immunostimulatory potential, it clearly appears that radiotherapy as it is prescribed and delivered nowadays often alters the host's immunity toward a suboptimal state. This may impair the full recovery of a sustained and efficient antitumor immunosurveillance posttreatment. An emerging concept is arising from this awareness and consists of reconsidering the way of designing radiation treatment planning, notably by taking into account the individualized risks of deleterious radio-induced immune alteration that can be deciphered from the planned beam trajectory through lymphocyte-rich organs. In this review, we critically appraise key aspects to consider while planning immunologically fitted radiotherapy, including the challenges linked to the identification of new dose constraints to immune-rich structures. We also discuss how pharmacologic immunomodulation could be advantageously used in combination with radiotherapy to compensate for the radio-induced loss, for example, with (i) agonists of interleukin (IL)2, IL4, IL7, IL9, IL15, or IL21, similarly to G-CSF being used for the prophylaxis of severe chemo-induced neutropenia, or with (ii) myeloid-derived suppressive cell blockers.

Longitudinal Assessment of Tumor-Infiltrating Lymphocytes in Primary Breast Cancer Following Neoadjuvant Radiation Therapy

PURPOSE

Tumor-infiltrating lymphocytes (TILs) have prognostic significance in several cancers, including breast cancer. Despite interest in combining radiation therapy with immunotherapy, little is known about the effect of radiation therapy itself on the tumor-immune microenvironment, including TILs. Here, we interrogated longitudinal dynamics of TILs and systemic lymphocytes in patient samples taken before, during, and after neoadjuvant radiation therapy (NART) from PRADA and Neo-RT breast clinical trials.

METHODS AND MATERIALS

We manually scored stromal TILs (sTILs) from longitudinal tumor samples using standardized guidelines as well as deep learning-based scores at cell-level (cTIL) and cell- and tissue-level combination analyses (SuperTIL). In parallel, we interrogated absolute lymphocyte counts from routine blood tests at corresponding time points during treatment. Exploratory analyses studied the relationship between TILs and pathologic complete response (pCR) and long-term outcomes.

RESULTS

Patients receiving NART experienced a significant and uniform decrease in sTILs that did not recover at the time of surgery (P < .0001). This lymphodepletive effect was also mirrored in peripheral blood. Our SuperTIL deep learning score showed good concordance with manual sTILs and importantly performed comparably to manual scores in predicting pCR from diagnostic biopsies. The analysis suggested an association between baseline sTILs and pCR, as well as sTILs at surgery and relapse, in patients receiving NART.

CONCLUSIONS

This study provides novel insights into TIL dynamics in the context of NART in breast cancer and demonstrates the potential for artificial intelligence to assist routine pathology. We have identified trends that warrant further interrogation and have a bearing on future radioimmunotherapy trials.

IFN-Type-I Response and Systemic Immunity in Rectal Adenocarcinoma Patients Treated with Conventional or Hypofractionated Neoadjuvant Radiotherapy

The IFN-type-I pathway is involved in radiotherapy (RT)-mediated immune responses. Large RT fractions have been suggested to potently induce this pathway. Neoadjuvant hypofractionated short-course (scRT) and conventional long-course (lcRT) RT applied for the treatment of locally advanced rectal adenocarcinoma patients provides a unique model to address the immuno-stimulatory properties of RT on a systemic level. We prospectively analyzed the IFNβ plasma levels and lymphocyte counts (LCs) of rectal adenocarcinoma patients before and after treatment with scRT (n = 22) and lcRT (n = 40). Flow cytometry was conducted to assess the effects on lymphocytic subpopulations in a subset of 20 patients. A statistically significant increase in the post-RT IFNβ plasma levels was noted in patients undergoing scRT (p = 0.004). Improved pathological tumor regression was associated with elevated post-RT IFNβ levels (p = 0.003). Although all patients experienced substantial lymphopenia after treatment, the post-RT LC of patients treated with scRT were significantly higher compared to lcRT (p = 0.001). Patients undergoing scRT displayed significantly lower percentages of regulatory CD4+/CD25+ T-cells after therapy (p = 0.02). scRT enables effective stimulation of the IFN-type-I pathway on a systemic level and confers decreased lymphocytic cytotoxicity and limited regulatory T-cell activation compared to lcRT, supporting its increasing role in immuno-RT trials.

Acute hematologic toxicity of radiation therapy - a comprehensive analysis and predictive nomogram

To investigate radiation-induced cytopenia and establish predictive nomograms for hematological toxicity, we reviewed 3786 patients aged 18 or older who received radiation monotherapy between 2010 and 2021 for non-hematologic malignancies. We collected data on patient background, treatment content and hematologic toxicities for 12 weeks after the start of radiotherapy. The patients were randomly divided into training and test groups in 7:3 ratio. In the training group, we conducted ordered logistic regression analysis to identify predictive factors for neutropenia, lymphocytopenia, anemia and thrombocytopenia. Nomograms to predict Grade 2-4 cytopenia were generated and validated in the test group. Grade 3 or higher hematologic toxicities were observed in 9.7, 44.6, 8.3 and 3.1% of patients with neutropenia, lymphocytopenia, anemia and thrombocytopenia, respectively. We identified six factors for neutropenia grade, nine for lymphocytopenia grade and six for anemia grade with statistical significance. In the analysis of thrombocytopenia, the statistical model did not converge because of a small number of events. Nomograms were generated using factors with high predictive power. In evaluating the nomograms, we found high area under the receiver operating characteristic curve values (neutropenia; 0.75-0.85, lymphopenia; 0.89-0.91 and anemia; 0.85-0.86) in predicting Grade 2-4 cytopenia in the test group. We established predictive nomograms for neutropenia, leukocytopenia and anemia and demonstrated high reproducibility when validated in an independent cohort of patients.

Lymphocyte recovery from radiation-induced lymphopenia in locally advanced esophageal squamous cell carcinoma: correlations with prognosis and lymphocyte-related organs

BACKGROUND

Limited studies explored the relationship between lymphocyte recovery after definitive concurrent chemoradiotherapy (dCCRT) and prognosis in esophageal squamous cell carcinoma (ESCC).

METHODS

ESCC patients with obtainable absolute lymphocyte counts (ALCs) at 6 months after dCCRT were screened from prospective trials. Patients were divided into groups according to the grade of ALC nadir during radiotherapy (G4 or G1-3) and lymphocyte recovery status, which was assessed by lymphocyte recovery index (LRI), calculated as the ratio of post- to pre-treatment lymphocyte counts. Cox analysis was conducted to evaluate the prognostic significance of lymphocyte recovery status. Irradiated relative volumes of the bone marrow (BM) and spleen and effective dose to immune cells (EDIC) were collected to identify their impacts on lymphocyte recovery status by logistic analysis.

RESULTS

232 patients were enrolled. In 69 patients with G4 ALC nadir (group A and B) and 163 patients with G1-3 ALC nadir (group C and D) during dCCRT, 27 (group A) and 67 (group C) patients showed an insufficient level of lymphocyte recovery (LRI < 60%), and 42 (group B) and 96 (group D) patients showed a satisfactory level of lymphocyte recovery (LRI ≥ 60%). Cox multivariable analysis revealed that inadequate lymphocyte recovery was significantly associated with worse overall survival (HR, 2.80 and 1.70) and local recurrence-free survival (HR, 2.82 and 1.60) both in group A vs group B and group C vs group D. Logistic analysis identified BM V5 (OR 4.24 and 2.29) as an independent predictor of inadequate lymphocyte recovery from G4 or G1-3 ALC nadir, respectively.

CONCLUSIONS

Insufficient lymphocyte recovery might serve as a valuable prognostic factor, regardless of whether patients experienced G4 or G1-3 ALC nadir during radiotherapy. Additionally, it was observed that a larger relative volume of BM receiving ≥ 5 Gy was correlated with a higher risk of insufficient lymphocyte recovery.

Effect of Radiation Therapy on Composition of Lymphocyte Populations in Patients with Primary Breast Cancer

BACKGROUND

Radiation therapy (RT) is an important step in the treatment of primary breast cancer as it is one of the leading contributors to cancer incidence among women. Most patients with this disease acquire radiation-induced lymphopenia in the early post-radiation period; however, little is known about the effect of RT on the composition of lymphocyte populations in such patients. This study was aimed at investigating the effect of adjuvant remote RT-performed in the classical mode for patients with primary breast cancer-on the main components of cell-mediated immunity (major lymphocyte populations), including those in patients receiving chemotherapy.

METHODS

Between 2020 and 2022, 96 patients with stage I-III breast cancer were included in this study. All patients in the final stage of complex treatment received RT via a 3D conformal technique (3DCRT). The clinical target volume of this RT included the breast or chest wall and locoregional lymphatics. Flow cytometry was used to assess the levels and phenotypes of circulating lymphocytes before and after RT (no more than 7 days before and after RT). The evaluation of the impact of polychemotherapy (PCT) was conducted to determine whether it was a risk factor for the onset of radio-induced lymphopenia (RIL) in the context of RT.

RESULTS

When assessing the immune status in the general group of patients (n = 96), before the start of adjuvant external beam radiotherapy (EBRT), the average number of lymphocytes was 1.68 ± 0.064 × 109/L; after the course of adjuvant EBRT, it decreased to 1.01 ± 0.044 × 109/L (p < 0.001). When assessing the absolute indicators of cellular immunity in the general group of patients with BC after a course of adjuvant EBRT, significant dynamics were revealed by the changes in all cell populations of lymphocytes (paired t-test, p < 0.05).

CONCLUSION

The adaptive immune system in breast cancer patients changed in the early post-radiation period. The absolute levels of B-, T- and natural killer cells significantly reduced after RT regardless of whether the patients previously underwent chemotherapy courses. RT for patients with primary breast cancer should be considered in clinical management because it significantly alters lymphocyte levels and should be considered when assessing antitumor immunity, as significant changes in T-cell immunity have been observed. In addition, the identified changes are critical if specific targeted therapy or immunotherapy is needed.

Prognostic impact of radiotherapy-induced-lymphopenia in patients treated with breast-conservative surgery

We investigated a prognostic impact of radiotherapy-induced lymphopenia (RIL) in breast cancer patients treated with breast-conservative surgery (BCS). We included 531 breast cancer patients who were treated with BCS and adjuvant radiotherapy. None of these received (neo)adjuvant chemotherapy. Pre- and post- absolute lymphocyte counts (ALC) were reviewed before and after radiotherapy. The primary endpoint was to evaluate recurrence-free survival (RFS) according to the pre-to-post ALC ratio. Binary logistic regression model was used to identify risk factors for RIL. Either continuous or categorical (> 2.4) pre-to-post ALC ratio was associated with RFS. In 531 patients receiving whole breast irradiation (WBI) and regional nodal irradiation (RNI), RFS was significantly reduced in the patients with high pre-to-post ALC ration (> 2.4). In multivariable analysis, low pre-to-post post ALC ratio was significantly related to decreased RFS in the multivariable analysis (HR 2.293, 95% CIs 1.110-4.735, P = 0.025). In 452 patients treated with WBI alone, high pre-to-post ALC ratio was still significantly associated with decreased RFS in the multivariable analysis (HR 2.708, 95% CIs 1.016-7.218, P = 0.046). In binary logistic regression analysis, RNI was only significant risk factor for clinically meaningful RIL. Our findings show that a markedly decrease in ALC during radiotherapy has a negative prognostic impact.

Impact of radiation dose to the immune system on disease progression and survival for early-stage non-small cell lung cancer treated with stereotactic body radiation therapy

OBJECTIVES

Although the effects of estimated dose of radiation to immune cells (EDRIC) in stage III NSCLC, LA-NSCLC, LS-SCLC and esophageal cancer on clinical outcomes have been studied, its impact in early-stage non-small cell lung cancer (ES-NSCLC) is unknown. In this study, we evaluated the role of EDRIC and identified the factors influencing EDRIC in this population.

METHODS AND MATERIALS

We retrospectively analyzed 211 pathologically confirmed ES-NSCLC patients who were treated with SBRT between 2007 and 2020. EDRIC was calculated based on the model developed by Jin et al. and improved by Ladbury et al. Kaplan-Meier method and Cox proportional hazards regression were adopted to estimate CSS, PFS, LPFS, and DMFS. Pearson correlation was used to assess the correlation between variables. We further validated our findings in an independent cohort of 119 patients with ES-NSCLC.

RESULTS

A total of 211 patients were included with median follow-up of 48 months in the training cohort. The median EDRIC was 2.178 Gy (range: 0.426-6.015). GTV showed a positive correlation with EDRIC (r = 0.707, P = 0.000). In multivariate analysis, higher EDRIC was significantly associated with worse CSS (HR = 1.468, P = 0.009) and DMFS (HR = 1.491, P = 0.016). Considering each EDRIC quartile, there was a significant difference in CSS between 1st and 4th and 1st and 3rd quartile (P = 0.000, P = 0.004, respectively); and DMFS between 1st and 4th,1st and 3rd, and 1st and 2nd quartile (P = 0.000, P = 0.000, P = 0.008, respectively). In the subgroup and validation cohort, EDRIC was also the important prognostic predictor of CSS and DMFS using multivariate analysis.

CONCLUSION

EDRIC was an independent predictor of CSS and DMFS in ES-NSCLC, and it was affected by GTV and tumor location. Though EDRIC is a critical determinant of treatment outcomes, it is quantifiable and potentially modifiable. Additional researches exploring the feasibility of achieving lower EDRIC while maintaining adequate tumor coverage during radiotherapy are warranted.

Anti-Tumor Immunity and Preoperative Radiovaccination: Emerging New Concepts in the Treatment of Breast Cancer

Neoadjuvant chemotherapy (NACT) for certain breast cancer (BC) subtypes confers significant tumor regression rates and a survival benefit for patients with a complete pathologic response. Clinical and preclinical studies have demonstrated that immune-related factors are responsible for better treatment outcomes, and thus, neoadjuvant immunotherapy (IO) has emerged as a means to further improve patient survival rates. Innate immunological "coldness", however, of specific BC subtypes, especially of the luminal ones, due to their immunosuppressive tumor microenvironment, hinders the efficacy of immune checkpoint inhibitors. Treatment policies aiming to reverse this immunological inertia are, therefore, needed. Moreover, radiotherapy (RT) has been proven to have a significant interplay with the immune system and promote anti-tumor immunity. This "radiovaccination" effect could be exploited in the neoadjuvant setting of BC and significantly enhance the effects of the already established clinical practice. Modern stereotactic irradiation techniques directed to the primary tumor and involved lymph nodes may prove important for the RT-NACT-IO combination. In this review, we provide an overview and critically discuss the biological rationale, clinical experience, and ongoing research underlying the interplay between neoadjuvant chemotherapy, anti-tumor immune response, and the emerging role of RT as a preoperative adjunct with immunological therapeutic implications in BC.

Predicting Severity of Radiation Induced Lymphopenia in Individual Proton Therapy Patients for Varying Dose Rate and Fractionation Using Dynamic 4-Dimensional Blood Flow Simulations

PURPOSE

Radiation-induced lymphopenia has gained attention recently as the result of its correlation with survival in a range of indications, particularly when combining radiation therapy (RT) with immunotherapy. The purpose of this study is to use a dynamic blood circulation model combined with observed lymphocyte depletion in patients to derive the in vivo radiosensitivity of circulating lymphocytes and study the effect of RT delivery parameters.

METHODS AND MATERIALS

We assembled a cohort of 17 patients with hepatocellular carcinoma treated with proton RT alone in 15 fractions (fx) using conventional dose rates (beam-on time [BOT], 120 seconds) for whom weekly absolute lymphocyte counts (ALCs) during RT and follow-up were available. We used HEDOS, a time-dependent, whole-body, blood flow computational framework, in combination with explicit liver blood flow modeling, to calculate the dose volume histograms for circulating lymphocytes for changing BOTs (1 second-300 seconds) and fractionations (5 fx, 15 fx). From this, we used the linear cell survival model and an exponential model to determine patient-specific lymphocyte radiation sensitivity, α, and recovery, σ, respectively.

RESULTS

The in vivo-derived patient-specific α had a median of 0.65 Gy^-1 (range, 0.30-1.38). Decreasing BOT to 1 second led to an increased average end-of-treatment ALC of 27.5%, increasing to 60.3% when combined with the 5-fx regimen. Decreasing to 5 fx at the conventional dose rate led to an increase of 17.0% on average. The benefit of both increasing dose rate and reducing the number of fractions was patient specificࣧpatients with highly sensitive lymphocytes benefited most from decreasing BOT, whereas patients with slow lymphocyte recovery benefited most from the shorter fractionation regimen.

CONCLUSIONS

We observed that increasing dose rate at the same fractionation reduced ALC depletion more significantly than reducing the number of fractions. High-dose-rates led to an increased sparing of lymphocytes when shortening the fractionation regimen, particularly for patients with radiosensitive lymphocytes at elevated risk.

Prognostic markers including immune and inflammatory factors predict outcomes in patients receiving postoperative radiation therapy for cholangiocarcinoma

PURPOSE

This study aimed to analyze treatment outcomes and prognostic markers, including immune and inflammatory factors, of postoperative radiation therapy (RT) administered to patients with cholangiocarcinoma (CCA).

METHODS

We retrospectively included 59 patients with CCA who underwent surgery and postoperative RT with curative intent from 2004 to 2019. Patients received external irradiation (50 Gy in 25 fractions) using three-dimensional RT. We analyzed prognostic factors of inflammation, such as pre-RT platelet count, hemoglobin, lymphocyte count ratio (LCR) of the leukocyte count, platelet-to-lymphocyte ratio (PLR), and neutrophil-to-lymphocyte ratio (NLR).

RESULTS

Tumor stages were distributed as follows: I (n = 8), II (n = 25), III (n = 15), and IVA (n = 11). The median follow-up was 24 months. Two-year overall survival (OS), cause-specific survival (CSS), progression-free survival (PFS), and locoregional control (LRC) rates were 59.5%, 62.0%, 40.1%, and 66.7%, respectively. Univariate analysis revealed that lower LCR was significantly associated with shorter PFS (p = 0.0446). There was no significant difference between the median baseline values of PLR and NLR; and age ≥75, positive regional lymph node metastases (N+), and chemotherapy after RT were significantly associated with poor OS. Multivariate analysis revealed a significant association of N+ with worse OS, PFS, and CSS and that lower LCR was significantly associated with better PFS (p = 0.0234). Among late toxicity events, two patients (3.38%) were suspected with therapy-related liver toxicity.

CONCLUSIONS

Lower LCR before RT was a better prognostic factor for postoperative RT of patients with CCA.

Radiation-Induced Lymphopoenia and Treatment Outcome in Hereditary Breast Cancer Patients

Many breast cancer (BC) predisposition genes encode proteins involved in DNA damage repair (DDR). Identification of germline pathogenic va-riants (PV) in DDR genes raises the question whether their presence can influence the treatment outcomes and potential radiation-induced toxicity in their carriers treated by adjuvant radiotherapy, which has not yet been answered conclusively. We retrospectively examined records of 213 BC patients treated by adjuvant radiotherapy, including 39 (18.3 %) BRCA1/2 PV carriers, 25 carriers (11.7 %) of PV in other breast cancer-predisposing genes, and 149 (70 %) non-carriers. Our goal was to examine 5-year disease-free survival (5y DFS) rates among the study groups and determine the impact of radiotherapy-induced lymphopoenia (RIL) on this outcome. While we found no significant difference in 5y DFS between non-carriers and carriers of BRCA mutations (86.4 % vs 78.4 % P = 0.24) or between non-carriers and other studied mutations (86.4 % vs 93.3 %; P = 0.27), respectively, we observed that the entire group of PV carriers had a significantly lower proportion of patients without RIL (P = 0.04) than the non-carriers. In contrast, subsequent analyses indicated a non-significant trend toward an increased 5y DFS in PV carriers with RIL. Our single-centre study indicated that the presence of PV in BC patients has an insignificant impact on DFS but can reduce the risk of RIL associated with adjuvant radiotherapy. It remains unclear whether this may result from the paradoxical activation of anti-tumour immunity in PV carriers with higher lymphocyte consumption resulting from higher immune effectiveness.

Meta-analysis and Critical Review: Association Between Radio-induced Lymphopenia and Overall Survival in Solid Cancers

Purpose

Immune system modulation, with the use of immune checkpoint inhibitors, has drastically changed the field of oncology. Strong preclinical data indicate that radiation therapy (RT) may enhance the response rate to such drugs via in situ vaccination, although these data do not consider immune radiotoxicity. This meta-analysis investigates whether radio-induced lymphopenia (RIL) is associated with overall survival (OS).

Methods and Materials

A systematic literature search and quantitative analysis were planned, conducted, and reported per the Preferred Reporting Items for Systematic Reviews and Meta-analyses and Quality of Reporting of Meta-analyses checklists. The literature from January 1990 to March 2021 was searched to identify clinical studies with OS data in patients treated with RT and presenting with lymphopenia. A random-effect model was employed for the meta-analysis. Heterogeneity was assessed using the I² statistic. Publication bias was estimated using a P-curve analysis.

Results

A total of 56 studies with 13 223 patients and 11 types of cancers were selected. The mean follow-up time was 35.9 months. Over a third of patients had RIL (37.25%). After removing outlying studies (n = 14), the between-study heterogeneity variance was estimated at t² = 0.018 (P = .01) with an I² value of 36.0% (95% confidence interval, 6%-56%). The results showed that RIL was significantly associated with worse OS (hazard ratio: 1.70; 95% confidence interval, 1.55-1.86; P < .01; 95% prediction interval, 1.27-2.26). A subgroup analysis was performed based on the type of primary tumor, and a difference between the subgroups was found (P < .01). Based on the P-curve analysis, a significant evidential value was found, and no significant publication bias was identified among the studies.

Conclusions

RIL is a significant prognostic factor for mortality in virtually all solid cancers. Pooled-effect estimates indicate a significantly reduced risk of death in patients without RIL. Tailoring RT regimens to spare the immune system and updating dosimetric constraints for new organs at risk, such as major blood vessels, organs with rich blood supplies, bones, and all lymph node areas, may improve prognoses.

The molecular basis of immuno-radiotherapy

PURPOSE

Radiotherapy (RT) and immunotherapy are powerful anti-tumor treatment modalities. Experimental research has demonstrated an important interplay between the cytotoxic effects of RT and the immune system. This systematic review provides an overview of the basics of anti-tumor immunity and focuses on the mechanisms underlying the interplay between RT and immune anti-tumor response that set the molecular basis of immuno-RT.

CONCLUSIONS

An 'immunity acquired equilibrium' mimicking tumor dormancy can be achieved post-irradiation treatment, with the balance shifted toward tumor eradication or regrowth when immune cells' cytotoxic effects or cancer proliferation rate prevail, respectively. RT has both immunosuppressive and immune-enhancing properties. The latter effect is also known as radio-vaccination. Its mechanisms involve up- or down-regulation of membrane molecules, such as PD-L1, HLA-class-I, CD80/86, CD47, and Fas/CD95, that play a vital role in immune checkpoint pathways and increased cytokine expression (e.g. INFα,β,γ, IL1,2, and TNFα) by cancer or immune cells. Moreover, the interactions of radiation with the tumor microenvironment (fibroblasts, tumor-infiltrating lymphocytes, monocytes, and dendritic cells are also an important component of radio-vaccination. Thus, RT may have anti-tumor vaccine properties, whose sequels can be exploited by immunotherapy agents to treat different cancer subtypes effectively.

Potential Molecular Mechanisms behind the Ultra-High Dose Rate "FLASH" Effect

FLASH radiotherapy, or the delivery of a dose at an ultra-high dose rate (>40 Gy/s), has recently emerged as a promising tool to enhance the therapeutic index in cancer treatment. The remarkable sparing of normal tissues and equivalent tumor control by FLASH irradiation compared to conventional dose rate irradiation—the FLASH effect—has already been demonstrated in several preclinical models and even in a first patient with T-cell cutaneous lymphoma. However, the biological mechanisms responsible for the differential effect produced by FLASH irradiation in normal and cancer cells remain to be elucidated. This is of great importance because a good understanding of the underlying radiobiological mechanisms and characterization of the specific beam parameters is required for a successful clinical translation of FLASH radiotherapy. In this review, we summarize the FLASH investigations performed so far and critically evaluate the current hypotheses explaining the FLASH effect, including oxygen depletion, the production of reactive oxygen species, and an altered immune response. We also propose a new theory that assumes an important role of mitochondria in mediating the normal tissue and tumor response to FLASH dose rates.

Severe radiation-induced lymphopenia during postoperative radiotherapy or chemoradiotherapy has poor prognosis in patients with stage IIB-III after radical esophagectomy: A post hoc analysis of a randomized controlled trial

Objective

To investigate whether radiation-induced lymphopenia (RIL) affects survival and identify the predictors of RIL in postoperative esophageal cancer.

Materials and methods

Post hoc analysis was conducted on data from 116 patients with esophageal cancer from a randomized controlled trial comparing adjuvant therapy with surgery alone. Doses of 54 Gy in 27 fractions was delivered in the postoperative radiotherapy (PORT) group and 50.4 Gy in 28 fractions combined with chemotherapy was delivered in postoperative concurrent chemoradiotherapy (POCRT) group. Blood counts were obtained before, during, and at first follow-up after treatment. Lymphopenia was graded per version 4.03 of the Common Terminology Criteria for Adverse Events. Disease-free survival (DFS) and overall survival (OS) were analyzed using the Kaplan-Meier method, and compared between groups using the log-rank test. Receiver operating characteristic curves identified thresholds for preventing grade 4 (G4) lymphopenia.

Results

Median follow-up duration was 56.0 months. During treatment, 16 patients (13.8%) had G4 lymphopenia. All cases of G4 lymphopenia occurred in group PORT (30.2% vs 0.0%, p<0.001). Baseline absolute lymphocyte count was comparable between G1-3 and G4 patients (2.0 ± 0.8 *10⁹/L vs 1.7 ± 0.5 *10⁹/L; p=0.101). The 3-year DFS was significantly lower in group G4 lymphopenia than that in group G1-3 (31.3% vs 57.6%, p=0.036). The 3-year OS was comparable between both groups (50.0% vs 66.5%, p=0.095). Logistic regression analysis revealed that exposed more thoracic marrow (TM V20 ≥75%; TVB V20 ≥71%), heart (V15 ≥40%) and PTV (volume ≥507 ml) were associated with G4 lymphopenia (p<0.05).

Conclusions

G4 RIL had poor disease-free survival, which may be related to more dose exposure of thoracic marrow and heart due to larger PTV. Reasonably reducing the radiation field combined with concurrent chemotherapy, or radiation dose constraints for these normal tissues may be sufficient to decrease the incidence of G4 lymphopenia, but further prospective trials are needed to verify the results.

Clinical Trial Registration

clinicaltrials.gov, identifier NCT02279134

Potential Determinants for Radiation-Induced Lymphopenia in Patients With Breast Cancer Using Interpretable Machine Learning Approach

Radiation-induced lymphopenia is known for its survival significance in patients with breast cancer treated with radiation therapy. This study aimed to evaluate the impact of radiotherapy on lymphocytes by applying machine learning strategies. We used Extreme Gradient Boosting (XGboost) to predict the event of lymphopenia (grade≥1) and conduced an independent validation. Then, we induced feature attribution analysis (Shapley additive explanation, SHAP) in explaining the XGboost models to explore the directional contribution of each feature to lymphopenia. Finally, we implemented the proof-of-concept clinical validation. The results showed that the XGboost models had rigorous generalization performances (accuracies 0.764 and ROC-AUC 0.841, respectively) in the independent cohort. The baseline lymphocyte counts are the most protective feature (SHAP = 5.226, direction of SHAP = -0.964). Baseline platelets and monocytes also played important protective roles. The usage of taxane only chemotherapy was less risk on lymphopenia than the combination of anthracycline and taxane. By the contribution analysis of dose, we identified that firstly lymphocytes were sensitive to a radiation dose less than 4Gy; secondly the irradiation volume was more important in promoting lymphopenia than the irradiation dose; thirdly the irradiation dose promoted the event of lymphopenia when the irradiation volume was fixed. Overall, our findings paved the way to clarifying the radiation dose volume effect. To avoid radiation-induced lymphopenia, irradiation volume should be kept to a minimum during the planning process, as long as the target coverage is not compromised.

Radiation Induced Lymphopenia Is Associated With the Effective Dose to the Circulating Immune Cells in Breast Cancer

Background

Lymphopenia is a known significant factor for treatment outcome in cancer patients, with underlying risk factor poorly understood in breast cancer. We hypothesize that the effective dose to the circulating immune cells (EDIC) which was related with lymphopenia in lung cancer will also have significant effect for radiation induced lymphopenia (RIL) in patients with breast cancer.

Material and Methods

Patients treated with adjuvant radiotherapy (RT) and with complete blood tests within one week from RT end/start (post/preRT) were eligible in this study. Radiation dosimetric factors were collected retrospectively, and EDIC for each patient was calculated based on the doses to lung, heart and total body according to the model description, as previously reported. RIL was defined by the CTCAE5.0 based on postRT peripheral lymphocyte count (PLC). Linear regression was first used to test the correlation between EDIC with post/preRT PLC ratio and postRT PLC, using all these as continuous variables. Normal tissue complication probability (NTCP) was used to develop models that predict the CTCAE graded RIL from EDIC.

Results

A total of 735 patients were eligible. The mean post/preRT PLC ratio was 0.66 (95% CI: 0.64-0.68) and mean EDIC of breast cancer was 1.70Gy (95% CI: 1.64-1.75). Both post/preRT PLC ratio and postRT PLC were significantly correlated with EDIC (P<0.001), with R² of 0.246. For patients with normal preRT PLC, the post/preRT PLC ratio was better associated with EDIC, and postRT PLC was expressed as PLC_preRT × (0.89 – 0.16 × EDIC). For patients with preRT lymphopenia, postRT PLC was better associated with EDIC and it was 1.1 – 0.17 × EDIC. Using binned EDIC as the dose variable, the bootstrap validated NTCPs fit the data nicely with R² of 0.93, 0.96, and 0.94 for grade-1, grade-2, and grade-3 RIL, respectively. The corresponding EDIC to induce 50% of grade-1, grade-2 and grade-3 RIL was 1.2, 2.1 and 3.7 Gy, respectively.

Conclusion

EDIC is a significant factor for RIL in patients with breast cancer, and may be used to compute the risk of lymphopenia in each individual patient with the use of the conventional NTCP modeling. External validation is needed before the EDIC can be used to guide RT plan.

Role of Vitamin C in Selected Malignant Neoplasms in Women

Since the first reports describing the anti-cancer properties of vitamin C published several decades ago, its actual effectiveness in fighting cancer has been under investigation and widely discussed. Some scientific reports indicate that vitamin C in high concentrations can contribute to effective and selective destruction of cancer cells. Furthermore, preclinical and clinical studies have shown that relatively high doses of vitamin C administered intravenously in ‘pharmacological concentrations’ may not only be well-tolerated, but significantly improve patients’ quality of life. This seems to be particularly important, especially for terminal cancer patients. However, the relatively high frequency of vitamin C use by cancer patients means that the potential clinical benefits may not be obvious. For this reason, in this review article, we focus on the articles published mainly in the last two decades, describing possible beneficial effects of vitamin C in preventing and treating selected malignant neoplasms in women, including breast, cervical, endometrial, and ovarian cancer. According to the reviewed studies, vitamin C use may contribute to an improvement of the overall quality of life of patients, among others, by reducing chemotherapy-related side effects. Nevertheless, new clinical trials are needed to collect stronger evidence of the role of this nutrient in supportive cancer treatment.

Incidence and Severity of Myelosuppression With Palbociclib After Palliative Bone Radiation in Advanced Breast Cancer: A Single Center Experience and Review of Literature

BACKGROUND

Palbociclib is a cyclin-dependent kinase (CDK) 4/6 inhibitor with a primary toxicity of myelosuppression, especially neutropenia, due to cytostatic CDK6 inhibition on bone marrow. Preclinical studies suggest palbociclib may enhance radiation toxicity, but this was only evaluated in limited case series of palliative radiotherapy and not specific to radiation targeting bony metastases.

PATIENTS AND METHODS

This was a single institution retrospective cohort study. We included female patients who initiated palbociclib for advanced breast cancer between 2015 and 2019. The primary exposure was receipt of palliative radiation to bony metastases within 1 year prior to starting palbociclib. The primary outcome was the incidence and severity of myelosuppression during cycle one. Secondary outcomes include treatment interruptions and cycle 2 dose reductions, with subgroup analysis of radiation timing, type, dose, and location.

RESULTS

Of the 247 patients, 47 received radiation to bone metastases. Only absolute lymphocyte count (ALC) after cycle one of palbociclib was significantly lower in the group receiving radiation (median ALC 0.84 vs. 1.10 K/mm³, P < .001), with similar rates of neutropenia, anemia, and thrombocytopenia. Patients who received ≥10 fractions radiation were more likely to have cycle one interrupted than those receiving shorter radiation courses (42.9% vs. 11.1%, P = .03). No radiation characteristics were associated with other hematologic toxicities or dose reduction.

CONCLUSION

Palliative bone radiation within 1 year prior to palbociclib initiation was associated with greater lymphopenia during the first cycle than patients unexposed to radiation, but not neutropenia, anemia, or thrombocytopenia that would modify treatment.

Evaluation of deep learning-based autosegmentation in breast cancer radiotherapy

Purpose

To study the performance of a proposed deep learning-based autocontouring system in delineating organs at risk (OARs) in breast radiotherapy with a group of experts.

Methods

Eleven experts from two institutions delineated nine OARs in 10 cases of adjuvant radiotherapy after breast-conserving surgery. Autocontours were then provided to the experts for correction. Overall, 110 manual contours, 110 corrected autocontours, and 10 autocontours of each type of OAR were analyzed. The Dice similarity coefficient (DSC) and Hausdorff distance (HD) were used to compare the degree of agreement between the best manual contour (chosen by an independent expert committee) and each autocontour, corrected autocontour, and manual contour. Higher DSCs and lower HDs indicated a better geometric overlap. The amount of time reduction using the autocontouring system was examined. User satisfaction was evaluated using a survey.

Results

Manual contours, corrected autocontours, and autocontours had a similar accuracy in the average DSC value (0.88 vs. 0.90 vs. 0.90). The accuracy of autocontours ranked the second place, based on DSCs, and the first place, based on HDs among the manual contours. Interphysician variations among the experts were reduced in corrected autocontours, compared to variations in manual contours (DSC: 0.89–0.90 vs. 0.87–0.90; HD: 4.3–5.8 mm vs. 5.3–7.6 mm). Among the manual delineations, the breast contours had the largest variations, which improved most significantly with the autocontouring system. The total mean times for nine OARs were 37 min for manual contours and 6 min for corrected autocontours. The results of the survey revealed good user satisfaction.

Conclusions

The autocontouring system had a similar performance in OARs as that of the experts’ manual contouring. This system can be valuable in improving the quality of breast radiotherapy and reducing interphysician variability in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-021-01923-1.

Association between treatment-related lymphopenia and survival in glioblastoma patients following postoperative chemoradiotherapy

PURPOSE

Our study investigated the association between treatment-related lymphopenia and overall survival (OS) in a series of glioblastoma (GBM) patients. We also explored clinical and dosimetric predictors of lymphocytes depletion.

METHODS

Between 2015 and 2019, 64 patients were treated at the same institution with postoperative chemoradiotherapy. Peripheral lymphocyte count (PLC) data and dose-volume histogram parameters were collected. Radiotherapy (RT) schedule consisted in standard total dose of 60 Gy in 30 daily fractions, with concomitant and adjuvant temozolomide (TMZ). Posttreatment acute absolute lymphopenia (nadir AAL) was calculated as a PLC lower than 1.0 × 10³/mm³. Acute relative lymphopenia (ARL) was expressed by the nadir-PLC/baseline-PLC ratio < 0.5. Nadir-PLC was the lowest PLC registered between the end of RT and the first month of follow-up. Survival rates were estimated with Kaplan-Meier curves. Clinical and dosimetric variables related to AAL/ARL and OS were identified by univariate and multivariate analyses.

RESULTS

A total of 57 patients were eligible and included in the analyses. The median PLC was significantly decreased following chemoradiotherapy (2180/mm³ vs 900/mm³). Median OS was 16 months (range 5-55 months), with no significant difference between patients who developed nadir AAL and those who did not (16 months vs 16.5 months; p = 0.304). When considering ARL vs non-ARL, median OS was 14 months vs 26 months (p = 0.013), respectively. In multivariate Cox regression only age, sex, extent of surgery, access to adjuvant chemotherapy and brain D98% were independently associated with OS.

CONCLUSION

Although iatrogenic immunosuppression could be associated with inferior clinical outcomes, our data show that treatment-related lymphopenia does not adversely affect GBM survival. Prospective studies are required to confirm these findings.

Risk factors for radiation induced lymphopenia in patients with breast cancer receiving adjuvant radiotherapy

Background

This study aimed to investigate radiation-induced lymphopenia and its potential risk factors in patients with breast cancer receiving adjuvant radiotherapy.

Methods

Breast cancer patients received adjuvant radiotherapy (RT) at our hospital with peripheral lymphocyte counts (PLC) at pre-and immediately after RT (post-RT) were eligible. The primary endpoints were any grade of lymphopenia post-RT and nadir-PLC/pre-PLC <0.8. Patient characteristics, tumor factors, and treatment factors were collected for risk assessment. Data are presented as mean and 95% confidence interval (CI) unless otherwise specified. Matched analysis was used to compare the statistical significance between different RT techniques.

Results

A total of 735 consecutive patients met the study criteria. The mean PLC was 1.58×10⁹/L before and 0.99×10⁹/L post-RT (P<0.001). At the end of RT, 60.5% of patients had lymphopenia. Univariate and multivariable logistic analyses showed that RT technique involving RapidArc, mean lung dose, and chemotherapy were significant risk factors (P<0.05) for lymphopenia. RT technique was the only significant risk factor (P<0.05) for nadir-PLC/pre-PLC <0.8. Patients treated with RapidArc had a significantly greater reduction of PLC along with greater V5 of the lungs, even after matching mean lung dose and radiated volume.

Conclusions

Lymphopenia is common in patients with breast cancer after adjuvant RT. RT technique is the only significant factor for lymphopenia and nadir-PLC/pre-PLC <0.8, suggesting the significance of RT technique choice to minimize lymphopenia and improve treatment outcomes.

Chemotherapy is a risk factor of lymphopenia before adjuvant radiotherapy in breast cancer

BACKGROUND

Lymphopenia can decrease immune function of the host and is a known risk factor for poor prognosis in malignant tumors. Radiation induced lymphopenia was common in patients with breast cancer and was also reported to have a negative effect on long-term outcome.

AIMS

Lymphopenia may be associated with baseline immune status before radiotherapy (RT). This study aimed to explore the rate and risk factors of lymphopenia before start of the adjuvant RT in patients with breast cancer.

METHODS

Patients with invasive breast cancer treated from March 2015 to February 2020 and with peripheral lymphocyte counts (PLC) available within 7 days from the beginning of RT were eligible for this study. Data were presented as mean and 95% confidence interval unless otherwise specified. The risk factors of low PLC before RT were identified using univariate and multivariable linear regressions.

RESULTS

A total of 1012 consecutive patients met the study criteria. The mean PLC before RT commencement was 1.58*10⁹ /L (95%CI: 1.55-1.62*10⁹ /L) with 15.2% (95%CI: 13.1%-17.6%) CTCAE defined lymphopenia, rendering 12.3%, 2.6%, 0.3%, and 0% for grade 1, 2, 3 and 4 respectively. Univariate and multivariable linear regression showed prior chemotherapy was the most significant risk factor (p < .001) for low PLC, while age, menopausal status and lymph node stage were not (all ps > .05). A total of 912 (90.1%, 95%CI: 88.1%-91.9%) patients had chemotherapy before adjuvant RT in this study. In patients with HR+/HER2- breast cancer, 69.0% (95%CI: 63.0%-74.5%) N0 and 98.1% (95%CI: 95.1%-99.5%) N1 had also received chemotherapy.

CONCLUSIONS

Patients with breast cancer might have lymphopenia from prior chemotherapy at the start of adjuvant RT which could have negative effect on long-term outcome. It is also noted that most of the patients with HR+/HER2-, early-stage breast cancer were treated with aggressive chemotherapy without knowing the risk of chemotherapy induced lymphopenia. Future study on predictive or prognostic multigene assays is warranted to avoid unnecessary chemotherapy and subsequent lymphopenia in patients with low risk breast cancer.

The Influence of Severe Radiation-Induced Lymphopenia on Overall Survival in Solid Tumors: A Systematic Review and Meta-Analysis

PURPOSE

Emerging evidence suggests a detrimental prognostic association between radiation-induced lymphopenia (RIL) and pathologic response, progression-free survival, and overall survival (OS) in patients who undergo radiation therapy for cancer. The aim of this study was to systematically review and meta-analyze the prognostic impact of RIL on OS in patients with solid tumors.

METHODS AND MATERIALS

PubMed/MEDLINE and Embase were systematically searched. The analysis included intervention and prognostic studies that reported on the prognostic relationship between RIL and survival in patients with solid tumors. An overall pooled adjusted hazard ratio (aHR) was calculated using a random-effects model. Subgroup analyses for different patient-, tumor-, treatment-, and study-related characteristics were performed using meta-regression.

RESULTS

Pooling of 21 cohorts within 20 eligible studies demonstrated a statistically significant association between OS and grade ≥3 versus grade 0-2 RIL (n = 16; pooled aHR, 1.65; 95% confidence interval [CI], 1.43-1.90) and grade 4 RIL versus grade 0-3 (n = 5; aHR, 1.53; 95% CI, 1.24-1.90). Moderate heterogeneity among aHRs was observed, mostly attributable to overestimated aHRs in 7 studies likely subject to model-overfitting. Subgroup analysis showed significant prognostic impact of grade ≥3 RIL in 4 brain tumor (aHR, 1.63; 95% CI, 1.06-2.51), 4 lung cancer (aHR, 1.52; 95% CI, 1.01-2.29), and 3 pancreatic cancer (aHR, 1.92; 95% CI, 1.10-3.36) cohorts.

CONCLUSIONS

This meta-analysis demonstrates a significant detrimental prognostic association between grade ≥3 lymphopenia and OS in patients receiving radiation therapy for solid tumors. This finding appears consistent for tumors of the brain, thorax, and upper abdomen and provides an imperative to further elucidate the potential survival benefit of lymphopenia-mitigating strategies.

Is a higher estimated dose of radiation to immune cells predictive of survival in patients with locally advanced non-small cell lung cancer treated with thoracic radiotherapy?

BACKGROUND AND PURPOSE

In previous studies, the estimated dose of radiation to immune cells (EDRIC) showed a correlation with overall survival (OS) of patients with locally advanced non-small cell lung cancer (LA-NSCLC) who received thoracic radiotherapy. However, several factors such as gross tumor volume (GTV) and lymph node (N) stage may impact EDRIC. The purpose of this study was to identify the factors influencing EDRIC and to further assess the prognostic relevance of EDRIC.

MATERIALS AND METHODS

We retrospectively analyzed 201 patients with LA-NSCLC who received radiotherapy between 2012 and 2017. EDRIC was calculated based on the model developed by Jin et al. Kaplan-Meier method and Cox proportional hazards regression were used to analyze the correlation of potential factors with OS, local progression-free survival (LPFS), and distant metastasis-free survival (DMFS). Spearman's rank correlation was used to assess the correlation between variables.

RESULTS

Both GTV and N stage showed a positive correlation with EDRIC (r = 0.347, P < 0.001 and r = 0.249, P < 0.001, respectively). EDRIC was independently associated with DMFS (HR 1.185, P < 0.001). GTV was associated with OS (HR 1.006, P < 0.001), LPFS (HR 1.003, P = 0.017), and DMFS (HR 1.003, P = 0.032). While using GTV as a stratification factor in Kaplan-Meier analysis, EDRIC showed a trend of negative correlation with OS in GTV ≤ 66.6 cm³ group (P = 0.061).

CONCLUSION

EDRIC was an independent prognostic factor for metastasis and it was affected by GTV and N stage. However, the effect of EDRIC on OS was influenced by GTV.

Charged Particle and Conventional Radiotherapy: Current Implications as Partner for Immunotherapy

Radiotherapy (RT) has been shown to interfere with inflammatory signals and to enhance tumor immunogenicity via, e.g., immunogenic cell death, thereby potentially augmenting the therapeutic efficacy of immunotherapy. Conventional RT consists predominantly of high energy photon beams. Hypofractionated RT regimens administered, e.g., by stereotactic body radiation therapy (SBRT), are increasingly investigated in combination with cancer immunotherapy within clinical trials. Despite intensive preclinical studies, the optimal dose per fraction and dose schemes for elaboration of RT induced immunogenic potential remain inconclusive. Compared to the scenario of combined immune checkpoint inhibition (ICI) and RT, multimodal therapies utilizing other immunotherapy principles such as adoptive transfer of immune cells, vaccination strategies, targeted immune-cytokines and agonists are underrepresented in both preclinical and clinical settings. Despite the clinical success of ICI and RT combination, e.g., prolonging overall survival in locally advanced lung cancer, curative outcomes are still not achieved for most cancer entities studied. Charged particle RT (PRT) has gained interest as it may enhance tumor immunogenicity compared to conventional RT due to its unique biological and physical properties. However, whether PRT in combination with immune therapy will elicit superior antitumor effects both locally and systemically needs to be further investigated. In this review, the immunological effects of RT in the tumor microenvironment are summarized to understand their implications for immunotherapy combinations. Attention will be given to the various immunotherapeutic interventions that have been co-administered with RT so far. Furthermore, the theoretical basis and first evidences supporting a favorable immunogenicity profile of PRT will be examined.

Systemic Inflammation Response Index (SIRI) Independently Predicts Survival in Advanced Lung Adenocarcinoma Patients Treated with First-Generation EGFR-TKIs

Background

Systemic inflammation response index (SIRI) has been reported to be an effective blood-based biomarker for predicting prognosis in various kinds of cancer patients. However, the prognostic role of SIRI in advanced lung adenocarcinoma patient remains unclear.

Methods

The aim of the present study is to evaluate the prognostic role of SIRI in EGFR-mutant advanced lung adenocarcinoma patients treated with first-generation EGFR-TKIs. A total of 245 patients who received gefitinib, erlotinib, or icotinib at the Second Xiangya Hospital were retrospectively evaluated. SIRI was defined as neutrophil count×monocyte/lymphocyte count. The optimal cut-off value was determined according to receiver operation characteristic curve analysis. Characteristics of patients were compared via chi-square test or Fisher’s exact test. Survivals were estimated by the Kaplan–Meier method and compared by the Log rank test. Multivariate analysis was estimated using the Cox proportional hazards model.

Results

It is showed that high SIRI was associated with male patient, smoker, worse ECOG PS, 19-DEL mutation. Kaplan–Meier survival analysis showed that ECOG PS, brain metastasis, SIRI were significantly correlated with progression-free survival (PFS), and gender, ECOG PS, brain metastasis, NLR and SIRI were significantly correlated with overall survival (OS). Multivariate analysis showed that SIRI and ECOG PS independently predict PFS and OS.

Conclusion

Our findings indicate that SIRI is an effective and convenient marker for predicting prognosis in advanced EGFR-mutant lung adenocarcinoma patients treated with first-generation TKI.

Lymphopenia and intratumoral lymphocytic balance in the era of cancer immuno-radiotherapy

INTRODUCTION

The immune response has been recognized as a major tumor-eradication component of radiotherapy.

OBJECTIVE

This review studies, under a clinical perspective, two contrasting effects of radiotherapy, namely immunosuppression and radiovaccination.

MATERIALS AND METHODS

We critically reviewed the available clinical and experimental experience on radiotherapy-induced lymphopenia.

RESULTS

Radiation-induced tumor damage promotes radio-vaccination, enhances cytotoxic immune responses, and potentiates immunotherapy. Nevertheless, radiotherapy induces systemic and intratumoral lymphopenia. The above effects are directly related to radiotherapy fractionation and field size/location, and tumor characteristics.

DISCUSSION

Hypofractionated stereotactic and accelerated irradiation better promotes radio-vaccination and produces less severe lymphopenia. Adopting cytoprotective policies and combining lympho-stimulatory agents or agents blocking regulatory lymphocyte activity are awaited to unmask the radio-vaccination effect, enhancing the efficacy immuno-radiotherapy.

CONCLUSION

Radiation-induced lymphopenia and immunosuppression are important issues that should be considered in the design of immuno-radiotherapy clinical trials.

Lymphopenia and clinical outcomes in patients with residual nodal disease after neoadjuvant chemotherapy for breast cancer

BACKGROUND

Patients with residual nodal disease after neoadjuvant chemotherapy for breast cancer have a poor prognosis. We wanted to evaluate whether lymphopenia after treatment for breast cancer impacted clinical outcomes.

MATERIALS AND METHODS

We assessed 99 patients with node-positive disease after neoadjuvant chemotherapy. Absolute lymphocyte count was recorded 1 year after radiation. Dates of local, regional, and distant failure were recorded. Time to event outcomes were evaluated using Kaplan-Meier analysis. Multivariable analysis determined factors predictive for overall survival.

RESULTS

Median follow-up was 44 months (range 3-150). Median age was 48 years (range 23-79). Twenty-six patients (26%) had lymphopenia 1 year after RT. Patients with lymphopenia had a greater incidence of regional (p = 0.03) and distant failure (p = 0.009) compared to those with normal lymphocyte counts and had a 6.05 greater risk of death (p = 0.0002).

CONCLUSIONS

In patients with residual nodal disease after neoadjuvant chemotherapy, lymphopenia after breast cancer treatment was associated with overall survival. The relationship between lymphopenia and breast cancer outcomes warrants further investigation.

Splenic Hematopoietic and Stromal Cells in Cancer Progression

Tumor-derived secretory factors orchestrate splenic hematopoietic and stromal cells to fuel metastasis. The spleen acts as a reservoir site for hematopoietic stem and progenitor cells, which are rapidly exploited as myeloid-derived suppressor cells at the cost of tumor-reactive lymphoid cells. Splenic erythroid progenitor cells and mesenchymal stromal cells contribute directly and indirectly to both tumor immune escape and the metastatic cascade. Animal models provide valuable mechanistic insights, but their translation to a clinical setting highlights specific challenges and open issues. In this review, we envision the exploitation of the spleen as a source for novel biomarkers and therapeutic approaches.

The Effect of High Dose Intravenous Vitamin C During Radiotherapy on Breast Cancer Patients' Neutrophil-Lymphocyte Ratio

Background: Breast cancer is very common, and the incidence is growing every year. Most breast cancers are treated with radiation after surgery. As a side effect of radiation therapy, inflammation, as well as the neutrophil-lymphocyte ratio (NLR), level increases. However, high NLR levels act as independent prognostic factors for increased mortality in all cancers. In this study, the authors investigated whether administration of vitamin C, which is effective in suppressing inflammation, may help to reduce high levels of NLR produced by radiation therapy. Methods: This study was performed retrospectively among 424 patients who were diagnosed with breast cancer and were treated with postoperative radiotherapy at Kosin University Gospel Hospital from January 2011 to December 2017. Among them, 354 patients received radiation therapy without vitamin C (the control group), and 70 experimental patients received vitamin C intravenously twice a week for at least 4 weeks during radiation therapy. The experimental group was divided into two groups according to the dose administrated: a low-dose vitamin C group (less than 1 g/kg, 52 patients) and a high-dose vitamin C group (more than 1 g/kg, 18 patients). The authors conducted three NLR measurements: before and after radiation therapy and at 3 months after radiation therapy; the authors then compared the change in NLR over time between the groups using repeated measures analysis of variance. Results: In the control group and the low-dose vitamin C-administered group, NLR was increased at the endpoint compared to before the radiotherapy, whereas NLR values in the high-dose vitamin C group were 8.4 ± 1.7, 5.9 ± 1.3, and 4.3 ± 1.5, showing a continuous decrease and a statistically significant difference (p_interaction = 0.033). These results were similarly observed in models adjusted by the patient's age and American Joint Committee on Cancer stage, with borderline significance (p_interaction = 0.065). Conclusions: Elevated NLR, a measure of systemic inflammation, has been associated with higher mortality cancer patients, including breast cancer patients. In this observational study, NLR was significantly decreased during radiation therapy in patients administered high-dose vitamin C.