Can dosimetric parameters predict acute hematologic toxicity in rectal cancer patients treated with intensity-modulated pelvic radiotherapy?

Retrospective cohort study for thrombocytopenia during concurrent chemoradiotherapy for rectal cancer

Background

The aim of this article was to establish the clinical prognostic models and identify the predictive radiation dosimetric parameters for thrombocytopenia during concurrent chemoradiotherapy for rectal cancer.

Methods

In this retrospective cohort study, patients with rectal adenocarcinoma undergoing concurrent long-term chemoradiotherapy were included. The primary outcome of interest was grade 2 or higher (2+) thrombocytopenia (platelet(PLT) count <75,000/μL). Secondary outcomes included: grade 1 or higher thrombocytopenia (PLT count<100,000/μL) and the PLT count during chemoradiotherapy and its nadir. The risk prediction model was developed by logistic regression to identify clinical predictors of 2+ thrombocytopenia. Univariate linear regression models were used to test correlations between radiation dosimetric parameters and the absolute PLT count at nadirs.

Results

This retrospective cohort comprised 238 patients. Fifty-four (22.6%) patients developed thrombocytopenia during concurrent chemoradiotherapy, while 15 (6.3%) patients developed 2+ thrombocytopenia. Four independently associated risk factors, including age, Alb level, PLT count, and chemotherapy regimen, were included in the final model and used to form a 2+ thrombocytopenia probability estimation nomogram. The C-index was 0.87 (95% CI: 0.78-0.96). The calibration plot showed a moderate agreement, and the Brier score was 0.047 (95% CI: 0.025-0.070). The total absolute volume of bone marrow irradiated by 5 Gy, 10 Gy and 15 Gy of radiation (BM-V5ab, BM-V10ab, BM-V15ab), calculated by the volume of bone marrow multiplied by the corresponding Vx, were identified as new predictors. The nadir of PLT was found to be negatively correlated with BM-V5ab (β = -0.062, P =0.030), BM-V10ab (β = -0.065, P =0.030) and BM-V15ab (β = -0.064, P =0.042).

Conclusion

The occurrence of 2+ thrombocytopenia during concurrent chemoradiotherapy for rectal cancer can be predicted by the patient's baseline status and chemoradiotherapy regimen, and low dose irradiation of bone marrow can affect the level of platelets during the treatment.

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.

Dosimetric correlation of bone marrow irradiation with acute hematological toxicity in concurrent chemoradiation of cervical carcinoma patients

Background

Many acute toxicities are associated with concurrent chemoradiation in cervical carcinoma, which includes burning micturition, burning defecation, pain lower abdomen, increased frequency of stools along with Acute Hematological Toxicity (AHT). AHT is often an expected adverse effect, which can lead to treatment interruptions and decreased response rates. The purpose of this study is to analyze if there are any dosimetric constraints on the volume of bone marrow irradiated with AHT in cervical carcinoma patients treated with concurrent chemoradiation.

Material and Methods

In this retrospective study of 215 patients, a total of 180 patients were eligible for analysis. Multiple parameters of bone marrow volumes (whole pelvis bone marrow and its sub-volumes--ilium, lower pelvis, and lumbosacral spine) which were contoured individually for all patients were assessed to have any statistically significant association with AHT.

Results

The median age of the cohort was 57 years and majority of cases were locally advanced (stage IIB-IVA: 88.3%). Grade I, II, III leukopenia was seen in 44, 25, and 6 patients, respectively. A statistically significant correlation between grade 2+ and 3+ leukopenia was seen if bone marrow V10, V20, V30, and V40 were more than 95%, 82%, 62%, and 38%, respectively. In subvolume analysis, volumes of lumbosacral spine V20, V30, and V40 more than 95%, 90%, and 65%, respectively, were statistically significant for AHT.

Conclusion

Bone marrow volumes should also be given a constraint and should be tried to be achieved so that it leads to minimal treatment breaks due to AHT.

Dosimetric parameters and absolute monocyte count can predict the prognosis of acute hematologic toxicity in cervical cancer patients undergoing concurrent chemotherapy and volumetric-modulated arc therapy

Purpose

To explore clinical and dosimetric predictors of acute hematologic toxicity (HT) in cervical cancer patients treated with concurrent chemotherapy and volumetric-modulated arc therapy (VMAT).

Methods and materials

We retrospectively reviewed the clinical data of 184 cervical cancer patients who had concurrent chemotherapy and VMAT. Hematological parameters were collected during the treatment period. The total pelvic bone (TPB) was delineated retrospectively for dose-volume calculations. To compare the differences between two groups, the normality test findings were used to run a paired-samples t-test or Wilcoxon signed-rank test. Pearson's correlation analysis or Spearman's correlation was used to testing the correlation between the two variables. Binary logistic regression analysis was used to analyze associations between HT and possible risk factors. The receiver operating characteristic curve(ROC) was used to evaluate the best cut-off point for dosimetric planning constraints.

Results

The nadir of absolute monocyte count (AMC) was found to be positively correlated with the nadir of absolute white blood cells (WBC) count (r = 0.5378, 95% CI 0.4227–0.6357, P < 0.0001) and the nadir of absolute neutrophil count(ANC) (r = 0.5000, 95% CI 0.3794–0.6039, P < 0.0001). The AMC decreased and increased before the ANC and WBC. In multivariate logistic regression analysis, the chemotherapy regimens and the TPB_V20 were independent risk factors for developing grade ≥ 3 HT. The optimal TPB_V20 cut-off value identified by ROC curves and the Youden test was 71% (AUC = 0.788; 95% CI 0.722–0.845; P value < 0.001).

Conclusions

The changing trend of AMC can be used as an effective predictor for the timing and severity of the ANC/WBC nadirs and prophylactic G-CSF administration. Maintain TPB_V20 < 71% and selecting single-agent cisplatin or carboplatin could significantly reduce grade ≥ 3 HT in cervical cancer patients undergoing concurrent chemoradiotherapy.

The Impact of Pelvic Nodal Radiotherapy on Hematologic Toxicity: A Systematic Review with Focus on Leukopenia, Lymphopenia and Future Perspectives in Prostate Cancer Treatment

INTRODUCTION

Hematologic toxicity (HT), particularly leukopenia, is a common side-effect of oncologic treatments for pelvic malignancies. Pelvic nodal radiotherapy (PNRT) has been associated with HT development mainly through incidental bone marrow (BM) irradiation; however, several questions remain about the clinical impact of radiotherapy-related HT. Herein, we perform a systematic review of the available evidence on PNRT and HT.

MATERIALS AND METHODS

A comprehensive systematic literature search was performed through EMBASE. Hand searching and clinicaltrials.gov were also used.

RESULTS

While BM-related dose-volume parameters and BM-sparing techniques have been more thoroughly investigated in pelvic malignancies such as cervical, anal, and rectal cancers, the importance of BM as an organ-at-risk has received less attention in prostate cancer treatment.

CONCLUSIONS

We examined the available evidence regarding the impact of PNRT on HT, with a focus on prostate cancer treatment. We suggest that BM should be regarded as an organ-at-risk for patients undergoing PNRT.

Proton beam therapy in rectal cancer: A systematic review and meta-analysis

INTRODUCTION

Locally advanced rectal cancer is often treated with neoadjuvant chemoradiotherapy and surgery. Radiotherapy carries significant risk of toxicity to organs at risk (OAR). Proton beam therapy (PBT) has demonstrated to be effective in other cancers, delivering equivalent dosimetric radiation but with the benefit of improved sparing of OAR. This review compares dosimetric irradiation of OAR and oncological outcomes for PBT versus conventional photon-based radiotherapy in locally advanced rectal cancer.

METHODS

An electronic literature search was performed for studies with comparative cohorts receiving proton beam therapy and photon-based radiotherapy for rectal cancer.

RESULTS

Eight articles with a total of 127 patients met the inclusion criteria. There was significantly less irradiated small bowel with PBT compared to three-dimensional conformal radiation therapy (3DCRT) and intensity-modulated radiation therapy (IMRT) (MD -17.01, CI [-24.06, -9.96], p < 0.00001 and MD -6.96, CI [-12.99, -0.94], p = 0.02, respectively). Similar dosimetric results were observed for bladder and pelvic bone marrow. Three studies reported clinical and oncological results for PBT in recurrent rectal cancer with overall survival reported as 43 %, 68 % and 77.2 %, and one study in primary rectal cancer with 100 % disease free survival.

CONCLUSION

PBT treatment plans revealed significantly less irradiation of OAR for rectal cancer compared to conventional photon-based radiotherapy. Trials for recurrent rectal cancer and PBT have shown promising results. There are currently no ongoing clinical trials for primary rectal cancer and PBT. More research is required to validate its potential role in dose escalation, higher complete response rate and organ preservation without increasing toxicity.

Bone Marrow Suppression during Postoperative Radiation for Bladder Cancer and Comparative Benefit of Proton Therapy—Phase 2 Trial Secondary Analysis

Purpose

For patients with high-risk bladder cancer (pT3⁺ or N⁺), local regional failure remains a challenge after chemotherapy and cystectomy. An ongoing prospective phase 2 trial (NCT01954173) is examining the role of postoperative photon radiation therapy for high-risk patients using volumetric modulated arc therapy. Proton beam therapy (PBT) may be beneficial in this setting to reduce hematologic toxicity. We evaluated for dosimetric relationships with pelvic bone marrow (PBM) and changes in hematologic counts before and after pelvic radiation therapy and explored the potential of PBT treatment plans to achieve reductions in PBM dose.

Materials and Methods

All enrolled patients were retrospectively analyzed after pelvic radiation per protocol with 50.4 to 55.8 Gy in 28 to 31 fractions. Comparative PBT plans were generated using pencil-beam scanning and a 3-beam multifield optimization technique. Changes in hematologic nadirs were assessed using paired t test. Correlation of mean nadirs and relative PBM dose levels were assessed using the Pearson correlation coefficient (CC).

Results

Eighteen patients with a median age of 70 were analyzed. Mean cell count values after radiation therapy decreased compared with preradiation therapy values for white blood cells (WBCs), absolute neutrophil count (ANC), absolute lymphocyte count (all P < .001), and platelets (P = .03). Increased mean PBM dose was associated with lower nadirs in WBC (Pearson CC −0.593, P = .02), ANC (Pearson CC −0.597, P = .02), and hemoglobin (Pearson CC −0.506, P = .046), whereas the PBM V30 to V40 correlated with lower WBC (Pearson CC −0.512 to −0.618, P < .05), and V20 to V30 correlated with lower ANC (Pearson CC −0.569 to −0.598, P < .04). Comparative proton therapy plans decreased the mean PBM dose from 26.5 Gy to 16.1 Gy (P < .001) and had significant reductions in the volume of PBM receiving doses from 5 to 40 Gy (P < .001).

Conclusion

Increased PBM mean dose and V20 to V40 were associated with lower hematologic nadirs. PBT plans reduced PBM dose and may be a valuable strategy to reduce the risk of hematologic toxicity in these patients.

Effect of Pelvic Bone Marrow Sparing Intensity Modulated Radiation Therapy on Acute Hematologic Toxicity in Rectal Cancer Patients Undergoing Chemo-Radiotherapy

BACKGROUND

While chemo-radiotherapy improves local control in patients with locally advanced rectal cancer, it can also increase acute hematological toxicity (HT), which leads to poor outcomes. Patients receiving bone marrow radiation have been shown to develop acute HT. However, the safety and efficacy of bone marrow sparing is undetermined. The aim of our study was to explore the feasible dosimetric constraints for pelvic bone marrow (PBM) that can be widely used in rectal cancer patients undergoing chemo-radiotherapy.

METHODS

112 rectal cancer patients were selected and divided into the PBM sparing IMRT group (60 cases) and the non-PBM sparing IMRT group (52 cases). All patients underwent pelvic radiotherapy with concurrent capecitabine-based chemotherapy. The PBM dosimetric constraints in the PBM sparing IMRT group were set to:V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%. An independent sample t test was applied for the dose-volume parameters, and Chi-squared analysis was applied for clinical parameters and adverse events.

RESULTS

The radiation dose to PBM (V5~V45, Dmean, P<0.05), PBM sub-regions (V10~V35, Dmean, P<0.05) and both femoral heads (V5~V40, Dmean, P<0.05) decreased significantly in the PBM sparing IMRT group compared with that of the non-PBM sparing IMRT group (P<0.05). There was no significant difference in any dose-volume parameters of the bladder and small bowel in either groups, and none in the planning target volume (PTV) dose homogeneity and conformity (P>0.05). For acute HT observation, the incidence of grade 3 acute HT (χ2 = 7.094, P=0.008) was significantly reduced in patients treated with PBM sparing IMRT compared with patients treated with non-PBM sparing IMRT. There was no statistical difference in the incidence of vomiting, diarrhea, fatigue, anorexia, nausea, hand-foot syndrome, cystitis, perianal pain and perianal dermatitis in patients of both groups (P >0.05).

CONCLUSIONS

Applying PBM dosimetric constraints (V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%) can significantly reduce the radiation dose to PBM. The patients treated with PBM sparing IMRT had a lower incidence of acute HT compared with those treated with non-PBM sparing IMRT. Applying the PBM dosimetric constraints proposed by our study can benefits the patients with rectal cancer undergoing capecitabine-based chemo-radiotherapy.

Which Bone Marrow Sparing Strategy and Radiotherapy Technology Is Most Beneficial in Bone Marrow-Sparing Intensity Modulated Radiation Therapy for Patients With Cervical Cancer?

Background

To evaluate the dosimetric parameters of different bone marrow sparing strategies and radiotherapy technologies and determine the optimal strategy to reduce hematologic toxicity associated with concurrent chemoradiation (cCRT) for cervical cancer.

Methods

A total of 15 patients with Federation International of Gynecology and Obsterics (FIGO) Stage IIB cervical cancer treated with cCRT were re-planned for bone marrow (BM)-sparing plans. First, we determined the optimal BM sparing strategy for intensity modulated radiotherapy (IMRT), including a BMS-IMRT plan that used total BM sparing (IMRT-BM) as the dose-volume constraint, and another plan used os coxae (OC) and lumbosacral spine (LS) sparing (IMRT-LS+OC) to compare the plan without BM-sparing (IMRT-N). Then, we determined the optimal technology for the BMS-IMRT, including fixed-field IMRT (FF-IMRT), volumetric-modulated arc therapy (VMAT), and helical tomotherapy (HT). The conformity and homogeneity of PTV, exposure volume of OARs, and efficiency of radiation delivery were analyzed.

Results

Compared with the IMRT-N group, the average volume of BM that received ≥10, ≥20, ≥30, and ≥40 Gy decreased significantly in both two BM-sparing groups, especially in the IMRT-LS+OC group, meanwhile, two BMS-IMRT plans exhibited the similar effect on PTV coverage and other organs at risk (OARs) sparing. Among three common IMRT techniques in clinic, HT was significantly less effective than VMAT and FF-IMRT in the aspect of BM-Sparing. Additionally, VMAT exhibited more efficient radiation delivery.

Conclusion

We recommend the use of VMAT with OC and LS as separate dose-volume constraints in cervical cancer patients aiming at reducing hematologic toxicity associated with cCRT, especially in developing countries.

[Pelvic irradiation and hematopoietic toxicity: A review of the literature]

Pelvic bone marrow is the site of nearly 50% of total hematopoiesis. Radiation therapy of pelvic lymph node areas, and cancers located near the bony structures of the pelvis, exposes to hematological toxicity in the range of 30 to 70%. This toxicity depends on many factors, including the presence or absence of concomitant chemotherapy and its type, the volume of irradiated bone, the received doses, or the initial hematopoietic reserve. Intensity modulated radiation therapy allows the optimisation of dose deposit on at risk organs while providing optimal coverage of target volumes. However, this suggests that dose constraints should be known precisely to limit the incidence of radiation side effects. This literature review focuses firstly on pelvic lymph node areas and bony volumes nearby, then on the effects of irradiation on bone marrow and the current dosimetric constraints resulting from it, and finally on hematological toxicities by carcinologic location and progress in reducing these toxicities.

Pelvic bone marrow sparing intensity modulated radiotherapy reduces the incidence of the hematologic toxicity of patients with cervical cancer receiving concurrent chemoradiotherapy: a single-center prospective randomized controlled trial

Purpose

To test the efficacy and feasibility of pelvic bone marrow sparing intensity modulated radiotherapy (PBMS-IMRT) in reducing grade 2 or higher hematological toxicity (HT2+) for patients with cervical cancer treated with concurrent chemoradiotherapy.

Methods and materials

A total of 164 patients with Stage Ib2–IIIb cervical cancer were prospectively enrolled from March 2018 to March 2019 at a single center and were randomly allocated into the PBMS group or the control group. The control group received weekly cisplatin concurrently with IMRT, followed by intracavitary brachytherapy. The PBMS group additionally received PBM dose constraint. The dosimetric parameters of the pelvic bone (PB) and the subsites including hip bone (HIP) and lumbosacral spine (LSS) and the corresponding bone marrow were recorded. The endpoint of the trial was acute hematologic or gastrointestinal toxicity. Receiver operating characteristic curves were used to derive optimal dosimetric planning constraints.

Results

Eighty-two patients in the PBMS group and 82 in the control group were enrolled for statistical analysis. The incidence of HT2+ in the PBMS group was 50.0%, significantly lower than the 69.5% incidence in the control group (P = 0.02). Patients with PB V40 ≥ 28% were more likely to experience HT2+ (OR = 2.85, P = 0.006), while the incidence of grade 2 or higher gastrointestinal toxicity (GT2+) events did not differ significantly between the two groups (P > 0.05). Dosimetric parameters of LSS showed stronger associations with HT2+ than other subsites. The patients with LSS V10 ≥ 87% and LSS mean ≥ 39 Gy were more likely to experience HT2+ (OR = 3.13, P = 0.001;OR = 3.03, P = 0.002, respectively).

Conclusion

PBMS-IMRT reduced HT compared with IMRT alone. Efforts to maintain LSS V10 < 87%, LSS mean < 39 Gy and PB V40 < 28% simultaneously may reduce the risk of HT2 +.

Trial registration

The trial was registered with Chinese clinical trial registry (ChiCTR1800015069).

Dose-volume parameters of MRI-based active bone marrow predict hematologic toxicity of chemoradiotherapy for rectal cancer

Purpose

Magnetic resonance imaging (MRI) is routinely used for locoregional staging of rectal cancer and offers promise for the prediction of hematologic toxicity. The present study compares the clinical utility of MRI-based active bone marrow (BMact) delineation with that of CT-based bone marrow total (BMtot) delineation for predicting hematologic toxicity.

Methods

A prospective cohort study was performed. Eligible patients had stage II/III rectal cancer and qualified for preoperative chemoradiotherapy. The BMact areas on T1-weighted MRI were contoured. The impact of the dose–volume parameters of BMact/BMtot and clinical data on hematologic toxicity were assessed. Basic endpoints were the occurrence of grade 3/4 hematologic toxicity and peripheral blood parameters reaching a nadir. Linear regression models were generated for the nadirs and receiver operating characteristic (ROC) curves for the occurrence of grade 3/4 hematologic toxicity.

Results

Thirty-five patients were enrolled. Women presented higher dose–volume parameters of BMact, BMtot, and lymphocyte nadir (ALCnadir%) than men. Models for the prediction of ALCnadir% (V5-V20BMtot, V5-V30BMact) and platelet nadir (PLTnadir%; V5-V10BMtot, V5-V20BMact) were statistically significant. In the ROC curves, a baseline lymphocyte level of 1.81 × 10³/ml was adopted as the cutoff for predicting grade 3/4 lymphopenia, with specificity of 77.8% and sensitivity of 73.1%. The multivariate linear regression model for ALCnadir% had R² = 0.53, p = 0.038. In the tenth step of selection, V5BMact (p = 0.002) and gender (p = 0.019) remained. The multivariate linear regression model for PLTnadir% had R² = 0.20, p = 0.34. In the sixth step of selection, V15BMact remained (p = 0.026).

Conclusion

The dose–volume parameters of BMact serve as better predictors of ALCnadir% and PLTnadir% than BMtot.

[Preoperative intensity-modulated radiotherapy of rectal cancers: Relevance and modalities]

Preoperative radiotherapy boosted by chemotherapy is a recommended treatment in locally advanced rectal cancers. This treatment is delivered by three dimensional conformal irradiation, which is usually well tolerated but can induce potential toxicity such as rectitis, cystitis and hematologic adverse effects. Intensity-modulated radiotherapy, widely available nowadays, allows optimization of volume covering and sparing of organs at risk such as bladder and bone marrow. This review presents relevant clinical situations and requirements for a beneficial and safe preoperative irradiation of rectal cancers by intensity-modulated technique. This technique is compared to three-dimensional conformal radiotherapy.

Chemoradiation and granulocyte-colony or granulocyte macrophage-colony stimulating factors (G-CSF or GM-CSF): time to think out of the box?

Concerns have been raised about potential toxic interactions when colony-stimulating factors (CSFs) and chemoradiation are concurrently performed. In 2006, the ASCO guidelines advised against their concomitant use. Nevertheless, with the development of modern radiotherapy techniques and supportive care, the therapeutic index of combined chemotherapy, radiotherapy, and CSFs is worth reassessing. Recent clinical trials testing chemoradiation in lung cancer let investigators free to decide the use of concomitant CSFs or not. No abnormal infield event was reported after the use of modern radiotherapy techniques and concomitant chemotherapy regimens. These elements call for further investigation to set new recommendations in favour of the association of chemoradiation and CSFs. Moreover, radiotherapy could induce anticancer systemic effects mediated by the immune system in vitro and in vivo. With combined CSFs, this effect was reinforced in preclinical and clinical trials introducing innovative radioimmunotherapy models. So far, the association of radiation with CSFs has not been combined with immunotherapy. However, it might play a major role in triggering an immune response against cancer cells, leading to abscopal effects. The present article reassesses the therapeutic index of the combination CSFs-chemoradiation through an updated review on its safety and efficacy. It also provides a special focus on radioimmunotherapy.

Association of pre-surgery to pre-radiotherapy lymphocyte counts ratio with disease-free survival in rectal cancer patients receiving neoadjuvant concurrent chemoradiotherapy

Background

Colorectal cancer is the fourth most common cancer globally and neoadjuvant concurrent chemoradiotherapy (nCRT) and surgery are the standard treatments for locally advanced colorectal carcinoma. This study investigated the association between dynamic changes in absolute lymphocyte counts (ALCs) and disease-free survival (DFS) in rectal cancer patients receiving nCRT and identified factors associated with these changes.

Methods

We retrospectively examined 34 patients with locally advanced rectal cancer who received nCRT followed by surgery and adjuvant chemotherapy. The association between ALCs and DFS and that between ALCs and downstaging were analyzed and potential clinical- and treatment-related factors related to dynamic changes in ALCs were subsequently evaluated. The patient eligibility criteria were as follows: pathologically confirmed rectal adenocarcinoma, clinical stages II–III, ≥ 18 years of age, and so on. Pre-RTL was defined as ALCs obtained before the initiation of nCRT and pre-SL was defined as ALCs obtained before surgery. We measured pre-SL to pre-RTL ratio (pre-SLR), DFS, and ALCs.

Results

The median ALC declined significantly during nCRT. A lower pre-SLR was associated with poorer DFS with statistical significance in Kaplan–Meier (p = 0.007), univariate regression (hazard ratio [HR] = 6.287, 95% confidence interval [CI] 1.374–28.781, p = 0.018), and multivariable regression (HR = 7.347, 95% CI 1.595–33.850, p = 0.011) analyses. Neither patient characteristics nor treatment-related factors were related to downstaging. The pelvic bone marrow (PBM) volume receiving at least 30 Gy (V30) was significantly associated with pre-SLR in the univariate (HR = 5.760, 95% CI 1.317–25.187, p = 0.020) and multivariable (HR = 5.760, 95% CI 1.317–25.187, p = 0.020) regression analyses.

Limitations

Our study had several limitations. The sample size was small and the study was performed in a selected population, which may limit the generalization of the findings.

Conclusions

Radiotherapy had a profound impact on the change in ALCs. A lower pre-SLR was significantly associated with poorer DFS in rectal cancer patients receiving nCRT. The V30 of PBM was a predictor of pre-SLR.

Optimal dose limitation strategy for bone marrow sparing in intensity-modulated radiotherapy of cervical cancer

BACKGROUND

To quantify the dosimetric parameters of different bone marrow sparing strategies and to determine the optimal strategy for cervical cancer patients undergoing postoperative intensity-modulated radiotherapy (IMRT).

METHODS

Fifteen patients with cervical cancer were selected for analysis. The planning target volume (PTV) and the organs at risks (OAR) including small bowel, bladder, rectum, femoral heads, os coxae (OC), lumbosacral spine (LS) and bone marrow (BM) were contoured. For each patient, four IMRT plans with different strategies were generated, including one plan without BM as the dose-volume constraint, namely IMRT (N) plan, and three bone marrow sparing (BMS-IMRT) plans. The three BMS-IMRT plans used the BM, OC, OC and LS respectively, as the BM OAR, namely as IMRT (BM), IMRT (OC) and IMRT (OC + LS) plans. Dose volumes for the target and the OARs were compared using analysis of variance (ANOVA).

RESULTS

Compared with IMRT (N) plans, the dose to the small bowel, bladder, rectum and femoral heads showed no increase in the three BMS-IMRT plans. However, the irradiated dose to BM, OC and LS significantly decreased. In particular, the mean dose of BM, OC and LS decreased by about 5Gy (p < 0.05) in IMRT (BM) plans while the average volume receiving ≥20, ≥30, ≥40Gy decreased by 7.1-24.2%. The LS volume receiving 40Gy showed the highest decrease (about 31.2%, p < 0.05) in IMRT (OC + LS) plans. On the other hand, in comparison with IMRT (BM), IMRT (OC) reduced the dose volume of to the OC, but increased the dose to LS while IMRT (OC + LS) plans reduced both the OC and the LS volume at all dose levels. Specifically, the V20 of OC and LS in the IMRT (OC + LS) plan decreased by 11.5 and 11.2%, respectively.

CONCLUSION

By introducing the os coxae and lumbosacral spine as the dose-volume constraints, the IMRT plans exhibited the best sparing of the bone marrow without compromising the dose to surrounding normal structures. Therefore, we recommend adding the os coxae and lumbosacral spine as the BM OAR in such plans.

Impact of Chemotherapy Regimens on Normal Tissue Complication Probability Models of Acute Hematologic Toxicity in Rectal Cancer Patients Receiving Intensity Modulated Radiation Therapy With Concurrent Chemotherapy From a Prospective Phase III Clinical Trial

Purpose: To determine whether there are differences in bone marrow tolerance to chemoradiotherapy (CRT) between two chemotherapy regimens according to FOWARC protocol and how chemotherapy regimens affect radiation dose parameters and normal tissue complication probability (NTCP) modelings that correlate with acute hematologic toxicity (HT) in rectal cancer patients treated with intensity modulated radiation therapy (IMRT) and concurrent chemotherapy.

Materials and Methods: One hundred and twenty-eight rectal cancer patients who received IMRT from a single institution were recruited from Chinese FOWARC multicenter, open-label, randomized phase III trial. We assessed HT in these patients who were separated into two groups: Oxaliplatin (L-OHP) + 5- fluorouracil (5FU) (FOLFOX, 70 of 128) and 5FU (58 of 128). The pelvic bone marrow (PBM) was divided into three subsites: lumbosacral spine (LSS), ilium (I), and lower pelvic (LP). The endpoint for HT was grade ≥3 (HT3+) and grade ≥2 (HT2+) leukopenia, neutropenia, anemia and thrombocytopenia. Logistic regression was used to analyze the association between HT2+/HT3+ and dosimetric parameters. Lyman-Kutcher-Burman (LKB) model was used to calculate NTCP.

Results: Sixty-eight patients experienced HT2+: 22 of 58 (37.9%) 5FU and 46 of 70 (65.7%) FOLFOX (p = 0.008), while twenty-six patients experienced HT3+: 4 of 58 (6.9%) 5FU and 22 of 70 (31.4%) FOLFOX (p = 0.016). PBM and LP dosimetric parameters were correlated with HT2+ in the 5FU group but not in the FOLFOX group. No PBM dosimetric parameters were correlated with HT3+ in both groups. For PBM, NTCP at HT3+ was 0.32 in FOLFOX group relative to 0.10 in 5FU subset (p < 0.05).

Conclusion: Patients receiving FOLFOX have lower BM tolerance to CRT than those receiving 5FU. Low-dose radiation to the PBM is predictive for HT2+ in patients who received 5FU. NTCP modeling in FOLFOX group predicts much higher risk of HT3+ than 5FU group.

Efficacy and safety of consolidation chemotherapy during the resting period in patients with local advanced rectal cancer

It remains controversial as to whether a long interval between neoadjuvant chemoradiotherapy (NCRT) and surgery may provide clinical benefits for patients with local advanced rectal cancer (LARC). The addition of consolidation chemotherapy during the resting period was recently considered as a treatment option. The present study aimed to verify the efficacy and safety of consolidation chemotherapy during the resting period in patients with LARC. A total of 156 patients with local advanced stage T3-4N0-2 rectal cancer were enrolled between January 2010 and July 2016. Patients were divided into two groups, those who received consolidation chemotherapy prior to surgery (n=76) and the control group who did not (n=80). Multivariate logistic regression and the Kaplan-Meier method were used to explore the predictors of pathological complete response (pCR) and survival. The demographic and tumor characteristics were comparable between the two groups. The consolidation group yielded significantly higher pCR and near pCR rates compared with the control group (P=0.015). Patients in the consolidation group who also underwent standard adjuvant chemotherapy displayed improved 3-year disease-free survival (DFS) compared with the control group (P=0.036). Notably, the addition of consolidation chemotherapy between NCRT and surgery did not significantly increase the incidence of surgical complications and grade 3 or 4 toxicities when compared with the control group. Consolidation chemotherapy was associated with increased pCR/near pCR rates and improved 3-year DFS, and displayed a manageable safety profile. The present study provided primary evidence for the efficacy and safety of consolidation chemotherapy in LARC. Further prospective studies are warranted in the future to verify these results.

Dosimetric analysis and comparison of reduced longitudinal cranial margins of VMAT-IMRT of rectal cancer

Background

The cranial border of the target volume (TV) in rectal cancer patients treated with neoadjuvant chemoradiation (nCRT) is mostly defined at the level of L5/S1. However, current studies have shown that relapse cranially of the target volume after neoadjuvant nCRT and surgery is very rare. A reduction of cranial TV margins could be reasonable to reduce toxicity to the organs at risk (OAR). In this study we compared the dose distribution to the OAR for different cranial longitudinal margins using a dose-volume histogram (DVH) analysis.

Methods

Ten patients with loco regional advanced rectal cancer were analysed retrospectively. All patients were planned for Volumetric Arc Therapy Radiation Therapy (VMAT). Next to the original PTV (PTV0), three new planning target volumes (PTV) were defined for each patient: The PTV0 reduced by 1 cm, 2 cm and 3 cm on cranial extension. For each PTV a treatment plan with a total dose of 50.4 Gy with daily doses of 1.8 Gy was calculated. Dose to the OAR were evaluated and compared.

Results

For the bone marrow, the small bowel and the peritoneal space all clinically relevant relative dose parameters (V10-V50) as well as the Dmedian could be significantly reduced with every cranial target volume reduction of 1 cm. For V10 of the peritoneal space the dose could be nearly halved with a 3 cm shortened TV. After TV reduction of 3 cm also for the urinary bladder a significant dose reduction of the Dmedian could be achieved.

Conclusions

Considering the very low recurrence rates in the TME and IMRT era, the distribution patterns of these relapses as well as the relevant side effects of nCRT, we would agree with existing recommendations of reduction of the cranial target volume in nCRT treated rectal cancer patients.

Dose to Pelvic Bone Marrow Defined with FDG-PET Predicts for Hematologic Nadirs in Anal Cancer Patients Treated with Concurrent Chemo-radiation

PURPOSE

To investigate whether irradiated volume of pelvic active bone marrow (^ACTBM) may predict decreased blood cells nadirs in anal cancer patients undergoing concurrent chemo-radiation.

METHODS

Forty-four patients were analyzed and pelvic active bone marrow (^ACTBM) was characterized employing ¹⁸FDG-PET. Dosimetric parameters on dose-volume histograms were correlated to nadirs with generalized linear modeling.

RESULTS

^ACTBM mean dose was significantly correlated to white blood cell (β = -1.338; 95%CI: -2.455/-0.221; p = 0.020), absolute neutrophil count (β = -1.651; 95%CI: -3.284/-0.183; p = 0.048), and platelets (β = -0.031; 95%CI: -0.057/-0.004; p = 0.024) nadirs. Other dosimetric parameters were found to be correlated (^ACTBM-V_10,-V_20,-V₃₀and-V₄₀).

CONCLUSIONS

¹⁸FDG-PET is able to define active bone marrow and may predict for decreased blood cells count nadirs.

Factors affecting acute myelosuppression induced by radiotherapy and chemotherapy for rectal cancer

AIM

To identify the factors influencing acute myelosuppression induced by radiotherapy and chemotherapy in patients with rectal cancer.

METHODS

From June 2016 to June 2017, 64 rectal cancer patients who underwent synchronous radiotherapy and chemotherapy at our hospital were included. Univariate and Logistic regression analyses were performed to analyze the relationship between pelvic dose parameters and grade 2 acute bone marrow suppression. Three parts of the pelvis, including the lower pelvis, sacrum, and ilium were delineated in the radiotherapy system. Clinical factors analyzed included clinical stage, radiotherapy and chemotherapy, age, gender, and original pigment level. Pelvic dose volume parameters included lower pelvic, sacral, iliac, and pelvic V5, V10, V15, V20, V25, V30, V35, V40, V45, and V50, the average dose (Dmean), and the maximum dose (Dmax).

RESULTS

There were 40 (62.5%) cases of acute myelosuppression in the 64 included patients. Univariate analysis showed that chemotherapy, sex, iliac V20 and V30, and lumbosacral V45 were the main factors associated with acute myelosuppression. Logistic regression analysis showed that iliac V30 and chemotherapy were the main risk factors for acute myelosuppression. Receiver operating characteristic (ROC) analysis showed that the threshold of iliac V30 was 46%.

CONCLUSION

Iliac V30 is an independent risk factor for acute myelosuppression induced by radiotherapy and chemotherapy in patients with rectal cancer. In the treatment of colorectal cancer, the relationship between the local control rate and acute bone marrow suppression should be considered, and iliac V30 should be controlled to < 46% when formulating chemotherapy plan, which can effectively reduce the incidence rate of acute bone marrow suppression.

Radiotherapy dose led to a substantial prolongation of survival in patients with locally advanced rectosigmoid junction cancer: a large population based study

Radiotherapy is widely applied for locally advanced rectal cancer (RC) to improve both local control and long-term outcomes. However, the efficacy of radiotherapy for rectosigmoid junction cancer (RSC) is still undetermined. Here, we identified 10074 patients who were diagnosed with locally advanced RSC from Surveillance, Epidemiology, and End-Results (SEER) cancer registry. These patients were divided into three subgroups according to different therapy strategies, including surgery alone, surgery plus preoperative radiotherapy and surgery plus postoperative radiotherapy. 5-year cancer-specific survival (CSS) and 5-year overall survival (OS) were obtained. Kaplan-Meier methods and Cox regression models were used to estimate the correlations between prognostic factors and survival outcomes.The 5-year CSSs for RSC patients treated with pre- and postoperative radiotherapy were 72.3% and 72.2%, which were significantly higher than surgery alone (64.8%). The 5-year OSs for RSC patients treated with pre- and postoperative radiotherapy were 71.6% and 71.2%, which were higher than surgery alone (64.0%). In the separate analyses of stage II and III RSC patients, the similar trends were also obtained. In addition, pre- and postoperative radiotherapy were equally identified as valuable prognostic factors for better survival outcomes in RSC patients. Furthermore, the results following propensity score matching also confirmed that the long-term survivals of RSC patients were improved following radiotherapy. In conclusion, locally advanced RSCpatients could obtain potential long-term survival benefits from radiotherapy. A prospective randomized control trial should be performed to further validate the strength of evidence in current study.

Irradiation of anatomically defined pelvic subsites and acute hematologic toxicity in anal cancer patients undergoing chemoradiation

PURPOSE

Chemoradiation for the treatment of anal cancer is known to cause significant hematologic toxicity (HT). We sought to investigate if radiation dose to specific pelvic subsites is associated with increased HT risk.

METHODS AND MATERIALS

Forty-five patients with nonmetastatic anal cancer who received definitive chemoradiation with intensity modulated radiation therapy and concurrent mitomycin-C and 5-fluorouracil were studied. Total pelvic bone marrow (TBM) was divided into 3 subsites: lumbosacral bone marrow (LSBM), including the entire sacrum and L5 vertebral body; iliac bone marrow (IBM) extending from the iliac crests to the superior border of the femoral head; and lower pelvic bone marrow, including the pubic bones, ischia, acetabula, and proximal femurs. The primary endpoint was absolute neutrophil count (ANC) nadir during or within 2 weeks of treatment completion. Generalized linear modeling was used to analyze the correlation between the equivalent uniform dose (with an "a" value of 0.5) to the individual pelvic subsites and the various hematologic endpoints. Age, body mass index, sex, baseline blood counts, and immunosuppression were analyzed as potential covariates.

RESULTS

Mean ± standard deviation ANC nadir was 0.77 × 10⁹/L (±0.66 × 10⁹/L). Grades 3+ and 4+ neutropenia occurred in 71.1% and 44.4% of patients, respectively. In addition to radiation dose to pelvic bone marrow, baseline ANC was the only significant predictor of hematologic toxicity on multivariable analysis and was included in all models. The equivalent uniform doses of TBM, LSBM, and IBM were each significantly associated with neutropenia. The model performance of TBM (adjusted R² = 0.226) was similar to both LSBM (adjusted R² = 0.206) and IBM (adjusted R² = 0.249).

CONCLUSIONS

Radiation doses to TBM, LSBM, and IBM were individually associated with HT, suggesting that sparing just a portion of pelvic bone marrow is insufficient to decrease rates of clinically significant bone marrow suppression.

Hematologic toxicity in anal cancer patients during combined chemo-radiation: a radiation oncologist perspective

INTRODUCTION

Hematologic toxicity is an important side effect occurring in patients affected with anal cancer, undergoing combined radio-chemotherapy, with consistent clinical meaningfulness. Areas covered: Since more than a half of bone marrow is comprised within the pelvic region, the radiation dose received by this functional compartment is crucial. Modern imaging modalities may provide a useful tool to identify bone marrow and new delivery technology may enhance the radiation oncologist's possibility to selectively spare these structures, potentially decreasing acute hematologic toxicity profile in this setting. Expert commentary: Correlation between dose to pelvic structures and acute hematologic toxicity has been studied in several oncological settings, mainly on a retrospective frame. Different dose metrics were found to be correlated including mean doses and different points within the dose-volume histogram ranging from low to medium-high doses. Several imaging modalities were used to identify bone marrow both morphological and functional. Several clinical endpoints were used. In general, accounting for bone marrow during the treatment planning process may be important to decrease the acute hematologic toxicity profile during concurrent chemo-radiation in anal cancer patients. The most appropriate strategy to address this issue need further investigation and deserve validation in a prospective clinical framework.

Lumbar-sacral bone marrow dose modeling for acute hematological toxicity in anal cancer patients treated with concurrent chemo-radiation

The aim of the study was to model acute hematologic toxicity (HT) and dose to pelvic osseous structures in anal cancer patients treated with definitive chemo-radiation (CT-RT). A total of 53 patients receiving CT-RT were analyzed. Pelvic bone marrow and corresponding subsites were contoured: ilium, lower pelvis and lumbosacral spine (LSBM). Dose-volume histograms points and mean doses were collected. Logistic regression was performed to correlate dosimetric parameters and ≥G3 HT as endpoint. Normal tissue complication probability (NTCP) was evaluated with the Lyman-Kutcher-Burman (LKB) model. Logistic regression showed a significant correlation between LSBM-mean dose and ≥G3 leukopenia (β coefficient 0.122; p = 0.030; 95% CI 0.012-0.233). According to NTCP modeling, the predicted HT probability had the following parameters: TD₅₀: 37.5 Gy, γ ₅₀: 1.15, m: 0.347. For node positive patients, TD₅₀: 35.2 Gy, γ ₅₀: 2.27, m: 0.176 were found. Node positive patients had significantly higher PBM-V₁₅ (Mean 81.1 vs. 86.7%; p = 0.04), -V₂₀ (Mean 72.7 vs. 79.9%; p = 0.01) and V₃₀ (Mean 50.2 vs. 57.3%; p = 0.03). Patients with a mean LSBM dose >32 Gy had a 1.81 (95% CI 0.81-4.0) relative risk to develop ≥G3 leukopenia. For node positive patients, those risks were 2.67 (95% CI 0.71-10). LKB modeling seems to suggest that LSBM-mean dose should be kept below 32 Gy to minimize ≥G3 HT in anal cancer patients treated with IMRT and concurrent chemotherapy. The contribution of LSBM dose in the development of HT above 25 Gy seems steeper in node positive patients.

Dose to specific subregions of pelvic bone marrow defined with FDG-PET as a predictor of hematologic nadirs during concomitant chemoradiation in anal cancer patients

To test the hypothesis that irradiated volume of specific subregions of pelvic active bone marrow as detected by (18)FDG-PET may be a predictor of decreased blood cells nadirs in anal cancer patients undergoing concurrent chemoradiation, we analyzed 44 patients submitted to IMRT and concurrent chemotherapy. Several bony structures were defined: pelvic and lumbar-sacral (LSBM), lower pelvis (LPBM) and iliac (IBM) bone marrow. Active BM was characterized employing (18)FDG-PET and characterized in all subregions as the volume having standard uptake values (SUVs) higher than SUVmean. All other regions were defined as inactive BM. On dose-volume histograms, dosimetric parameters were taken. Endpoints included white blood cell count (WBC), absolute neutrophil count (ANC), hemoglobin (Hb) and platelet (Plt) nadirs. Generalized linear modeling was used to find correlations between dosimetric variables and blood cells nadirs. WBC nadir was significantly correlated with LSBM mean dose (β = -1.852; 95 % CI -3.205/-0.500; p = 0.009), V10 (β = -2.153; 95 % CI -4.263/-0.721; p = 0.002), V20 (β = -2.081; 95 % CI -4.880/-0.112; p = 0.003), V30 (β = -1.971; 95 % CI -4.748/-0.090; p = 0.023) and IBM V10 (β = -0.073; 95 % CI -0.106/-0.023; p = 0.016). ANC nadir found to be significantly associated with LSBM V10 (β = -1.878; 95 % CI -4.799/-0.643; p = 0.025), V20 (β = -1.765; 95 % CI -4.050/-0.613; p = 0.030) and IBM V10 (β = -0.039; 95 % CI -0.066/-0.010; p = 0.027). Borderline significance was found for correlation between Plt nadir and LSBM V30 (β = -0.056; 95 % CI -2.748/-0.187; p = 0.060), V40 (β = -0.059; 95 % CI -3.112/-0.150; p = 0.060) and IBM V30 (β = -0.028; 95 % CI -0.074/-0.023; p = 0.056). No inactive BM subsites were found to be correlated with any blood cell nadir. (18)FDG-PET is able to define active bone marrow within pelvic osseous structures. LSBM is the strongest predictor of decreased blood cells nadirs in anal cancer patients undergoing concurrent chemoradiation.

Combined sunitinib and radiation therapy for preoperative treatment of soft tissue sarcoma: results of a phase I trial of the German interdisciplinary sarcoma group (GISG-03)

Background

Experimental data demonstrated that concurrent anti-angiogenic treatment with sunitinib may improve the efficacy of radiation therapy (RT). Here we report the results of a phase I trial performed within the German Interdisciplinary Sarcoma Group (GISG-03) of combined sunitinib and RT for neoadjuvant treatment of locally advanced soft tissue sarcoma (STS).

Methods

The primary endpoint of the study was to explore the recommended dose of sunitinib combined with RT for subsequent trials. Treatment response, postoperative complications after tumor resection and toxicity according to CTCAE 4.0 were secondary endpoints. The study used a 3 + 3 design. Patients received either 25 mg (dose level 1) or 37.5 mg (dose level 2) sunitinib two weeks prior to and throughout RT (28 × 1.8 Gy). Surgery was scheduled 5–8 weeks after completion of neoadjuvant treatment. Study registration: NCT01498835.

Results

Six patients were enrolled in dose level 1 and three patients in dose level 2. Median tumor size was 11 cm. Tumors were located in the retroperitoneum (4/9), lower leg (3/9) or trunk (2/9). At dose level 1, 1/6 patients developed dose limiting lymphopenia. At dose level 2, no patient developed dose limiting toxicity. Most frequent toxicities were hematological (8/9) and oral (5/9). Dose adjustments of sunitinib were necessary in 5/9 patients. All patients received full dose RT and underwent tumor resection (8/9 R0 and 1/9 R1). Local toxicity of RT did not exceed Grade 2. 2/9 patients had postoperative complications requiring re-intervention. Treatment response according to RECIST was as follows: partial response 1/9, stable disease 7/9, and progressive disease 1/9. Pathological examination revealed ≥ 95 % tumor necrosis in 3/9 resected specimens.

Conclusions

Combined sunitinib and RT was tolerable as neoadjuvant treatment for locally advanced STS patients regardless of tumor localization. The recommended sunitinib dose for subsequent trials is 37.5 mg.

Dosimetric predictors of acute hematologic toxicity during concurrent intensity-modulated radiotherapy and chemotherapy for anal cancer

PURPOSE

This study aimed at investigating whether the irradiated volume of pelvic bone marrow (PBM) and specific subsites may predict the occurrence of acute hematologic toxicity (HT) in anal cancer patients undergoing concurrent chemo-radiation.

METHODS

50 patients, submitted to IMRT and concurrent chemotherapy, were analyzed. Several bony structures were defined on planning-CT: PBM and lumbar-sacral (LSBM), lower pelvis (LPBM) and iliac (IBM) bone marrow. On dose-volume histograms, dosimetric parameters were taken. Endpoints included white blood-cell-count (WBC), absolute-neutrophil-count (ANC), hemoglobin (Hb) and platelet nadirs and acute hematologic toxicity (HT) according to RTOG scoring scale. Generalized linear modeling was used to find correlations between dosimetric variables and blood cell nadirs, while logistic regression analysis was used to test correlation with ≥G3 HT. Receiver Operating Characteristic (ROC) curve analysis was used to evaluate the optimal cut-off points for predictive dosimetric variables with the Youden method.

RESULTS

Maximum detected acute HT comprised 38 % of ≥G3 leukopenia and 32 % of ≥G3 neutropenia. Grade 2 anemia was observed in 4 % of patients and ≥G3 thrombocytopenia in 10 %. On multivariate analysis a higher PBM-V ₂₀ was associated with lower WBC nadir. Increased LSBM-V ₄₀ was correlated with a higher likelihood to develop ≥G3 HT. A cut-off point at 41 % for LSBM-V ₄₀ was found. Patients with LSBM-V ₄₀ ≥41 % were more likely to develop ≥G3 HT (55.3 vs. 32.4 %; p < 0.01).

CONCLUSIONS

Increased low-dose to pelvic bony structures significantly predicted for WBC decrease. Medium-high dose to specific osseous subsites was associated with a higher probability of HT. LSBM-V ₄₀ was a strong predictor of ≥G3 HT. A threshold at 41 % for LSBM-V ₄₀ could be used to limit HT.

Clinical application of precise radiotherapy in rectal cancer

Precise radiotherapy plays an important role in the comprehensive multidisciplinary therapy of rectal cancer. The mainstream technology is the intensity modulated radiation therapy (IMRT). The technique of repetitive body positioning and the filling of the bladder and rectum are the important factors influencing the accuracy and efficacy of radiotherapy for rectal cancer. The quality of life for patients with rectal cancer is highly affected by side effects associated with radiotherapy. The application of precise positioning technique and image guided radiotherapy (IGRT) can significantly contribute to the accurate delivery of radiotherapy to the region of rectal cancer to improve the local tumor control and reduce unnecessary exposure of normal tissues to irradiation. In this paper, the clinical application of precise positioning technique and the improvement of accurate delivery of radiotherapy are comprehensively reviewed.