Successful treatment of induced oligometastasis and repeated oligoprogression of advanced lung adenocarcinoma with immunotherapy and radiotherapy.

Highly active and durable systemic therapies such as targeted therapy and immunotherapy can convert widespread metastatic disease into oligometastatic status, for which metastasis-directed local intervention can control and potentially prolong survival. Radiation therapy is an effective therapeutic option for oligometastatic and oligoprogressive disease. Here, we present a case of induced oligometastasis and repeated oligoprogressive lung cancer in which more than 6 years of survival was achieved with a combination of immunotherapy and radiotherapy.

Hypofractionated Radiotherapy for Early-Stage Breast Cancer: A Propensity Score Matched Analysis.

BACKGROUND: In patients with early-stage breast cancer, the treatment results of hypofractionated radiation therapy (RT) and conventional RT are evaluated in efficacy and cost. METHODS: We retrospectively evaluated 280 patients with early-stage (Tis-2N0M0) breast cancer (including 100 hypofractionated RT patients) with regards to treatment outcomes according to the RT schedule. The median whole-breast RT dose was 42.56 Gy/16 fractions for hypofractionated RT and 50.4 Gy/28 fractions for conventional RT. Most patients (n = 260, 92.9%) additionally received a tumor bed boost RT. We used propensity score matching (PSM) analysis to balance the baseline risk factors for recurrence. The co-primary endpoints of this study were disease-free survival (DFS) and ipsilateral breast tumor recurrence (IBTR). DFS or IBTR was analyzed using the Kaplan-Meier survival curve and log-rank test. RESULTS: Total 89 pairs of matched patients (1:1 matching, n = 178) were finally evaluated. The median follow-up was 23.6 months. After matching, the 3-year DFS was 100% in the hypofractionated RT group and 98.4% in the conventional RT group; there was no significant difference in DFS between the groups (P = 0.374). Furthermore, the IBTR did not differ between the hypofractionated RT and conventional RT groups (P = 0.374) after matching. The 3-year overall survival was not different between two groups (both 100%). Hypofractionated RT saved 26.6% of the total cost of RT compared to conventional RT. Additionally, the acute skin toxicity rate (≥ grade 2) was also not significantly different between the groups (hypofractionated RT: 10.1% vs. conventional RT: 2.2%). CONCLUSION: Hypofractionated RT showed good IBTR and DFS, which were compatible to those in conventional RT in breast cancer. Hypofractionated RT is expected to be used more widely because of its low cost and convenience.

Maximum standardized uptake value at pre-treatment PET in estimating lung cancer progression after stereotactic body radiotherapy.

PURPOSE: This study aimed to identify the feasibility of the maximum standardized uptake value (SUVmax) on baseline 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) as a predictive factor for prognosis in early stage primary lung cancer treated with stereotactic body radiotherapy (SBRT). MATERIALS AND METHODS: Twenty-seven T1-3N0M0 primary lung cancer patients treated with curative SBRT between 2010 and 2018 were retrospectively evaluated. Four patients (14.8%) treated with SBRT to address residual tumor after wedge resection and one patient (3.7%) with local recurrence after resection were included. The SUVmax at baseline PET/CT was assessed to determine its relationship with prognosis after SBRT. Patients were divided into two groups based on maximum SUVmax on pre-treatment FDG PET/CT, estimated by receiver operating characteristic curve. RESULTS: The median follow-up period was 17.7 months (range, 2.3 to 60.0 months). The actuarial 2-year local control, progressionfree survival (PFS), and overall survival were 80.4%, 66.0%, and 78.2%, respectively. With regard to failure patterns, 5 patients exhibited local failure (in-field failure, 18.5%), 1 (3.7%) experienced regional nodal relapse, and other 2 (7.4%) developed distant failure. SUVmax was significantly correlated with progression (p = 0.08, optimal cut-off point SUVmax > 5.1). PFS was significantly influenced by pretreatment SUVmax (SUVmax > 5.1 vs. SUVmax ≤ 5.1; p = 0.012) and T stage (T1 vs. T2-3; p = 0.012). CONCLUSION: SUVmax at pre-treatment FDG PET/CT demonstrated a predictive value for PFS after SBRT for lung cancer.

Diabetes as a prognostic factor in HER-2 positive breast cancer patients treated with targeted therapy.

PURPOSE: Recent studies revealed that metabolic stress influences the outcomes of breast cancer treatment. We sought to evaluate the prognostic effect of type 2 diabetes and find the molecular mechanism of relapses in postoperative HER-2+ breast cancer patients treated with HER-2 targeted therapy. MATERIALS AND METHODS: We evaluated 190 HER-2+ breast cancer patients (pT1-4N0-2M0) who were treated with surgical resection and trastuzumab (HER-2 targeted therapy) between 2006 and 2015. Survival outcomes and failure patterns were compared between such patients with (n = 12) and without (n = 178) type 2 diabetes. RESULTS: The median follow-up period was 42.4 months (range 12.0-124.7 months). Twenty-one patients (11.1%) showed relapse (including nine patients with locoregional failure), and three patients (1.6%) died as a result of cancer relapse. One-third of the patients with diabetes experienced relapse (4/12, 33.3%). The 3-year disease-free survival (DFS) and overall survival (OS) rates were 90.7% and 98.6%, respectively. Diabetic patients showed shorter DFS compared with non-diabetic patients (p = 0.006, 74.1% vs. 91.9%). OS was also shorter in diabetic patients compared with non-diabetic patients (p = 0.017, 91.7% vs. 99.1%). Of our interest, the levels of HER-3 and its ligand neuregulin-1 were significantly increased in the tumor specimen in HER-2+ breast cancer patients suffering with type 2 diabetes than that in the euglycemic control group. CONCLUSIONS: Type 2 diabetes was associated with detrimental effects on survival in postoperative HER-2+ breast cancer patients who were treated with trastuzumab. The poor prognostic effect of diabetes in HER-2+ breast cancer patients could be associated with the high levels of HER-3 and neuregulin 1, thus it should be considered and evaluated more.

Feasibility Study of Phosphor Screen Containing Nano-Scale Anti-Reflection Layer for Improved Optical Properties in Indirect X-ray Detector.

With increasingly strict regulations regarding patient exposure, research on digital radiography technology has recently focused on indirect methods that can produce high-quality images for a low radiation dose. In particular, medical imaging systems based on indirect methods universally use rare-earth metal phosphors, because of their high atomic number and excellent luminescence efficiency. Thus, various studies aiming to improve the luminescence efficiency of phosphors have been conducted. Despite this research, however, the current luminescence efficiencies are insufficient. Here, we report a basic study aiming to develop a phosphor screen containing a three-quarter-wave optical-thickness layer to improve the light transmission efficiency. Specifically, the fabrication and measurement of a Gd2O2S:Tb phosphor screen containing a single three-quarter-wave optical-thickness layer is presented. The screen is fabricated via a screen-printing and spin-coating method. Based on histograms of the degree of luminescence and the pixel values, we demonstrate that the light transmission efficiency is improved by the three-quarter-wave optical-thickness layer. Note that analysis of the full width at half maximum of the pixel value distribution reveals the possibility of resolution loss when obtaining medical images. Overall, the results of this study confirm that the light transmission efficiency can be improved through use of a single-layer anti-reflection coating. However, because the emission spectrum of the Gd2O2S:Tb screen is in the 480-600-nm band, it is necessary to expand the areas exhibiting the lowest reflectance to the wavelengths at the edge of this band. Thus, further study should be conducted to optimize the optical thickness.

Adverse effect of excess body weight on survival in cervical cancer patients after surgery and radiotherapy.

PURPOSE: This study aimed to assess the effects of body mass index (BMI) on survival in cervical cancer patients who had undergone surgery and radiotherapy (RT). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 70 cervical cancer patients who underwent surgery and RT from 2007 to 2012. Among them, 40 patients (57.1%) had pelvic lymph node metastases at the time of diagnosis. Sixty-seven patients (95.7%) had received chemotherapy. All patients had undergone surgery and postoperative RT. Median BMI of patients was 22.8 kg/m2 (range, 17.7 to 35.9 kg/m2). RESULTS: The median duration of follow-up was 52.3 months (range, 16 to 107 months). Twenty-four patients (34.3%) showed recurrence. Local failure, regional lymph nodal failure, and distant failure occurred in 4 (5.7%), 6 (8.6%), and 17 (24.3%) patients, respectively. The 5-year actuarial pelvic control rate was 83.4%. The 5-year cancer-specific survival (CSS) and disease-free survival (DFS) rates were 85.1% and 65.0%, respectively. The presence of pelvic lymph node metastases (n = 30) and being overweight or obese (n = 34, BMI ≥ 23 kg/m2) were poor prognostic factors for CSS (p = 0.003 and p = 0.045, respectively). Of these, pelvic lymph node metastasis was an independent prognostic factor (p = 0.030) for CSS. CONCLUSION: Overweight or obese cervical cancer patients showed poorer survival outcomes than normal weight or underweight patients. Weight control seems to be important in cervical cancer patients to improve clinical outcomes.

Correction: Adverse effect of excess body weight on survival in cervical cancer patients after surgery and radiotherapy.

[This corrects the article on p. 48 in vol. 35.].

Eribulin Mesylate Combined with Local Treatment for Brain Metastasis from Breast Cancer: Two Case Reports.

The prognosis associated with brain metastasis arising from breast cancer is very poor. Eribulin is a microtubule dynamic inhibitor synthesized from halichondrin B, a natural marine product. In a phase III study (EMBRACE), eribulin improved overall survival in patients with heavily pretreated metastatic breast cancers. However, these studies included few patients with brain metastases. Metastatic brain tumors (MBT) were detected during first-line palliative chemotherapy in a 43-year-old woman with breast cancer metastasis to the lung and mediastinal nodes; the genetic subtype was luminal B-like human epidermal growth factor receptor 2 (HER2)-negative. Whole brain radiotherapy (WBRT) followed by eribulin treatment continuously decreased the size, and induced regression, of the MBT with systemic disease stability for 12 months. Another 48-year-old woman with metastatic breast cancer (HER2+ subtype) presented with MBT. Following surgical resection of the tumor, eribulin with concurrent WBRT showed regression of the MBT without systemic progression for 18 months.

Being Overweight or Obese Increases the Risk of Progression in Triple-Negative Breast Cancer after Surgical Resection.

This study aimed to evaluate the association between body mass index (BMI) and progression in triple-negative breast cancer (TNBC). We retrospectively reviewed the medical records of 50 patients with TNBC who underwent breast-conserving surgery or mastectomy between 2007 and 2014. All patients were classified according to BMI (median 23.5 kg/m(2), range 17.2-31.6 kg/m(2)): 31 patients (62%) were classified as being overweight or obese (BMI ≥ 23 kg/m(2)) and 19 patients (38%) were classified as having a normal body weight (BMI < 23 kg/m(2)). The median follow-up for patients was 31.1 months (range, 6.7-101.9 months). Progression occurred in 7 patients (14%), including 5 ipsilateral breast tumor recurrences, 2 regional lymph node metastases, and 5 distant metastases. Progression was significantly correlated with overweight or obese patients (P = 0.035), while none of the normal weight patients showed progression. The 3-year disease-free survival (DFS) and overall survival (OS) rates were 85.0% and 87.7%, respectively. DFS was significantly reduced in overweight or obese patients compared to that in normal weight patients (P = 0.035). However, OS was not significantly compromised by being overweight or obese (P = 0.134). In conclusion, being overweight or obese negatively affects DFS in TNBC patients.

Association between obesity and local control of advanced rectal cancer after combined surgery and radiotherapy.

PURPOSE: The association between metabolism and cancer has been recently emphasized. This study aimed to find the prognostic significance of obesity in advanced stage rectal cancer patients treated with surgery and radiotherapy (RT). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 111 patients who were treated with combined surgery and RT for clinical stage 2-3 (T3 or N+) rectal cancer between 2008 and 2014. The prognostic significance of obesity (body mass index [BMI] ≥25 kg/m(2)) in local control was evaluated. RESULTS: The median follow-up was 31.2 months (range, 4.1 to 85.7 months). Twenty-five patients (22.5%) were classified as obese. Treatment failure occurred in 33 patients (29.7%), including local failures in 13 patients (11.7%), regional lymph node failures in 5, and distant metastases in 24. The 3-year local control, recurrence-free survival, and overall survival rates were 88.7%, 73.6%, and 87.7%, respectively. Obesity (n = 25) significantly reduced the local control rate (p = 0.045; 3-year local control, 76.2%), especially in women (n = 37, p = 0.021). Segregation of local control was best achieved by BMI of 25.6 kg/m(2) as a cutoff value. CONCLUSION: Obese rectal cancer patients showed poor local control after combined surgery and RT. More effective local treatment strategies for obese patients are warranted.

Efficacy of Dose-Escalated Radiotherapy for Recurrent Colorectal Cancer.

PURPOSE: This study aimed to evaluate the effects of radiotherapy (RT) on progression-free survival (PFS) for patients with recurrent colorectal cancer. METHODS: We reviewed the records of 22 patients with recurrent colorectal cancer treated with RT between 2008 and 2014. The median radiation dose for recurrent disease was 57.6 Gy (range, 45-75.6 Gy). Patients were divided into 2 groups according to the type of RT: patients underwent RT without previous history of irradiation (n = 14) and those treated with secondary RT (reirradiation: n = 8) at the time of recurrence. RESULTS: The median follow-up period was 24.9 months (range, 4.5-66.6 months). Progression was observed in 14 patients (including 8 with loco-regional failure and 9 with distant metastases). Distant metastases were related to the RT dose (<70 Gy, P = 0.031). The 2-year loco-regional control (LRC), PFS, and overall survival (OS) rates were 74.6%, 45.1%, and 82.0%, respectively. The LRC rate was not different between the patients treated with RT for the first time and those treated with reirradiation (P = 0.101, 2-year LRC 79.5% vs. 41.7%). However, reirradiation was related to poor PFS (P = 0.022) and OS (P = 0.002). An escalated RT dose (≥70 Gy) was associated with a higher PFS (P = 0.014, 2-year PFS 63.5% vs. 20.8%). CONCLUSION: Salvage RT for locally recurrent colorectal cancer can be offered when surgery is impossible. Dose-escalated RT shows a possible benefit in reducing the risk of progression.

Addition of anti-neu antibody to local irradiation can improve tumor-bearing BALB/c mouse survival through immune-mediated mechanisms.

This study investigated the therapeutic effects of combined local irradiation and anti-HER2/neu antibody in a mixed tumor mouse model comprised of a nonmetastatic neu-positive tumor and a metastatic neu-negative tumor. While local irradiation alone could control the primary tumor in a dose-dependent manner, it did not improve mouse survival. Combined treatment comprised of local irradiation and anti-neu antibody of tumor-bearing BALB/c mice significantly improved mouse survival (P < 0.5), even though the tumor growth was similar to that of the irradiated-alone group. The combined treatment significantly reduced metastatic tumor masses in the lung and increased immune cell infiltration in primary tumor tissues. However, immune deficient nude mice with tumors did not exhibit prolonged survival in response to the combined treatment. Collectively, these results show that combined local irradiation and anti-neu antibody can elicit an immune-mediated abscopal effect to extend survival. Although the mechanism for abscopal effects induced by the combined treatment of radiation and anti-HER2/neu antibody was not elucidated, to our knowledge this is the first published study to describe the abscopal effect induced by the combination of local irradiation and the anti-HER2/neu antibody.

The effect of probiotics for preventing radiation-induced morphological changes in intestinal mucosa of rats.

Radiation therapy is an important treatment modality for abdominal or pelvic cancer, but there is a common and serious complication such as radiation-induced enteritis. Probiotics is reported to have positive effects against radiation-induced enteropathy. In this study, morphological changes of bowel mucosa were analyzed in rats to presume the effect of probiotics on radiation-induced enteritis and its correlation with radiation dose. A total of 48 adult male Sprague-Dawley rats were randomly assigned to two groups and received a solution containing 1.0×10(8) colony-forming units of Lactiobacillus acidophilus or water once daily for 10 days. Each of two groups was divided into three subgroups and abdomino-pelvic area of each subgroup was irradiated with 10, 15, and 20 Gy, respectively on the seventh day of feeding the solutions. All rats were sacrificed 3 days after irradiation and the mucosal thickness and villus height of jejunum, ileum and colon were measured. The morphological parameters of the small intestine represented significant differences between two solution groups irradiated 10 or 15 Gy, except for villus height of jejunum in 15 Gy-subgroup (P=0.065). There was no significant morphometric difference between two groups irradiated with 20 Gy of radiation. Probiotics appear to be effective for the morphological shortening of small intestinal mucosa damaged by radiation less than or equal to 15 Gy.

Analysis of biologically equivalent dose of stereotactic body radiotherapy for primary and metastatic lung tumors.

PURPOSE: The purpose of this study was to determine the optimal biologically equivalent dose (BED) for stereotactic body radiotherapy (SBRT) by comparing local control rates in proportion to various total doses and fractionation schedules. MATERIALS AND METHODS: Thirty-four patients with early non-small-cell lung cancer and a single metastatic lung tumor were included in this study. Differences in local control rates were evaluated according to gender, primary tumor site, response, tumor size, and BED. For comparison of BEDs, the prescribed dose for SBRT was stratified according to three groups: high (BED > 146 Gy), medium to high (BED, 106 to 146 Gy), and low to medium (BED < 106 Gy). RESULTS: For all patients, the overall local control rate was 85.3% at two years after treatment. Five local recurrences were observed, and, notably, all of them were observed in the low to medium BED group. Significantly higher local control rates were observed for patients with a complete response than for those with a partial response or stable disease (p < 0.001). Twenty-six patients with a tumor size of < 3 cm showed no dose-response relationship in the low to medium, medium to high, and high BED groups, whereas eight patients with a tumor size of ≥ 3 cm showed a significant dose-response relationship. The observed 2-year local recurrence-free survival rates in patients with a tumor size of < 3 cm and in those with a tumor size of ≥ 3 cm were 96.2% and 50.0%, respectively, which were significantly different (p=0.007). CONCLUSION: BED > 100 Gy is required in order to achieve a > 85% local control rate regardless of tumor size. The optimal dose for small tumors of < 3 cm appears to be within a range below 150 Gy BED. Escalation of BED to high levels (> 150 Gy) may be required for patients with a tumor size larger than 3 cm.

The suitability of absorbable mesh insertion for oncoplastic breast surgery in patients with breast cancer scheduled to be irradiated.

PURPOSE: The objective of this study was to investigate the influence of radiotherapy on the cosmetic outcome after immediate breast reconstruction using an absorbable mesh in breast cancer. METHODS: From July 2008 to July 2009, 35 breast cancer patients who received immediate breast reconstruction with absorbable mesh insertion at the time of breast conserving surgery followed by radiotherapy were retrospectively studied. RESULTS: In 91% of cases there was an excellent or good cosmetic outcome before the initiation of radiotherapy, and in 8.6% the outcome was fair at this point. However, 6 months after surgery and irradiation, the rate of excellent to good cosmetic outcomes had decreased to 60% and fair outcomes had increased to 25.7%. Contrary to the decreased rate of good cosmetic outcomes from 65.7% to 42.9% at 1 year after operation, the rate of fair to poor outcomes considerably increased from 8.6% to 57.1%. The significant factors affecting cosmetic outcomes were pathology, specimen volume, and the estimated percentage of breast volume excised (EPBVE). Chemotherapy affected the cosmetic outcome at borderline significance level. Age, breast volume tumor site, insertion of drain, radiation dose, and time elapsed between surgery and radiotherapy were not significantly associated with the cosmetic outcome. CONCLUSION: Applying an absorbable mesh for the immediate reconstruction of the breast should be carefully considered in patients with an EPBVE of over 30% who are scheduled to be irradiated.

Human lymphoma cells develop resistance to radiation in the presence of astrocytes in vitro.

BACKGROUND: Lymphomas growing in the central nervous system exhibit resistance to radiotherapy compared to lymphomas of the lymph nodes. Because astrocytes have been shown to reduce radiation-induced neuronal toxicity, this study hypothesized that astrocytes might protect lymphoma cells from radiation-induced cell killing. MATERIALS AND METHODS: A human lymphoma cell line, H9, and normal human astrocytes were grown in culture, exposed to radiation and assessed for cell viability, radiation sensitivity, glutathione content, induction of apoptosis and cell-cycle distribution. RESULTS: Cell survival assays demonstrated that H9 cells growing in an astrocyte-monolayer and also in an astrocyte-conditioned medium displayed radioresistance compared with H9 cells growing under standard conditions. The radioresistance correlated with accumulation of H9 cells in the G(2) phase of the cell cycle, suppression of radiation-induced apoptosis and coincided with a moderate increase in glutathione. CONCLUSION: The findings of this study suggest that astrocytes may play a role in the radioresistance exhibited by lymphomas of the central nervous system.

Volumetric changes in the lumpectomy cavity during whole breast irradiation after breast conserving surgery.

PURPOSE: This study was performed to evaluate the change in the lumpectomy cavity volumes before and after whole breast radiation therapy (WBRT) and to identify factors associated with the change of volume. MATERIALS AND METHODS: From September 2009 to April 2010, the computed tomography (CT) simulation data from 70 patients obtained before and after WBRT was evaluated. The lumpectomy cavity volumes were contoured based on surgical clips, seroma, and postoperative changes. Significant differences in the data from pre-WBRT CT and post-WBRT CT were assessed. Multiple variables were examined for correlation with volume reduction in the lumpectomy cavity. RESULTS: The mean and median volume reduction in the lumpectomy cavity after WBRT were 17.6 cm(3) and 16.1 cm(3), respectively with the statistical significance (p < 0.001). The volume reduction in the lumpectomy cavity was inversely correlated with time from surgery to radiation therapy (R = 0.390). The presence of seroma was significantly associated with a volumetric change in the lumpectomy cavity after WBRT (p = 0.011). CONCLUSION: The volume of lumpectomy cavity reduced significantly after WBRT. As the time from surgery to the start of WBRT increased, the volume reduction in the lumpectomy cavity during WBRT decreased. A strong correlation was observed between the presence of seroma and the reduced volume. To ensure appropriate coverage and to limit normal tissue exposure during boost irradiation in patients who has seroma at the time of starting WBRT, repeating CT simulation at boost planning is suggested.

Imexon augments sensitivity of human lymphoma cells to ionizing radiation: in vitro experimental study.

BACKGROUND: Imexon is an aziridine-containing small pro-oxidant molecule with promising antitumor activity in myeloma, lymphoma and lung and pancreatic cancer. Imexon is already in clinical trials in patients with advanced solid tumors. The present study examined the effects of imexon on H9 and Raji lymphoma cell lines in vitro when given in combination with ionizing radiation. MATERIALS AND METHODS: H9 and Raji lymphoma cells were grown in culture and exposed to imexon, radiation, or both. Cells were assessed for cell viability, glutathione content, induction of apoptosis, cell cycle distribution and also subject to Western blot analysis. RESULTS: Imexon inhibited cell proliferation in a dose-dependent manner. Imexon, given for 48 h prior to irradiation at a clinically achievable dose of 40 muM, potently enhanced the cell radiosensitivity. Imexon enhanced radiation-induced apoptosis and accumulated cells in G2/M phase of the cell cycle. Imexon induced caspase-3 activation and PARP cleavage. Alterations in glutathione levels were not observed at 40 microM of imexon. CONCLUSION: In conclusion, imexon efficiently augmented lymphoma cell radiosensitivity independently of glutathione and the underlying mechanisms include induction of apoptosis and cell cycle redistribution.

Influence of intravenous contrast agent on dose calculations of intensity modulated radiation therapy plans for head and neck cancer.

BACKGROUND AND PURPOSE: To evaluate the effect of an intravenous contrast agent (CA) on dose calculations and its clinical significance in intensity modulated radiation therapy (IMRT) plans for head and neck cancer. MATERIALS AND METHODS: Fifteen patients with head and neck cancer and involved neck nodes were enrolled. Each patient took two sets of computerized tomography (CT) in the same position before and after intravenous CA injections. Target volumes and organs at risk (OAR) were contoured on the enhanced CT, and then an IMRT plan of nine equiangular beams with a 6 MV X-ray was created. After the fusion of non-enhanced and enhanced CTs, the contours and the IMRT plan created from the enhanced CT were copied and placed to the non-enhanced CT. Doses were calculated again from the non-enhanced CT by the same IMRT plan. The radiation doses calculated from the two sets of CTs were compared with regard to planning target volumes (PTV) and the three OARs, both parotid glands and the spinal cord, by Wilcoxon's signed rank test. RESULTS: The doses (maximum, mean, and the dose of 95% of PTV received (D95%)) of PTV70 and PTV59.4 calculated from the enhanced CTs were lower than those from the non-enhanced CTs (p < 0.05), but the dose differences were less than 1% compared to the doses calculated from the enhanced CTs. The doses of PTV50.4, parotid glands, and spinal cord were not significantly different between the non-enhanced and enhanced CTs. CONCLUSIONS: The difference between the doses calculated from the CTs with and without CA enhancement was tolerably small, therefore using intravenous CA could be recommended for the planning CT of head and neck IMRT.