Target movement according to cervical lymph node level in head and neck cancer and its clinical significance

PURPOSE

To evaluate set-up error for head and neck cancer (HNC) patients according to each neck lymph node (LN) level. And clinical factors affecting set-up error were analyzed.

MATERIALS AND METHODS

Reference points (RP1, RP2, RP3, and RP4) representing neck LN levels I to IV were designated. These RP were contoured on simulation computed tomography (CT) and cone-beam CT of 89 HNC patients with the same standard. After image registration was performed, movement of each RP was measured. Univariable logistic regression analyses were performed to analyze clinical factors related to measured movements.

RESULTS

The mean value of deviation of all axes was 1.6 mm, 1.3 mm, 1.8 mm, and 1.5 mm for RP1, RP2, RP3, and RP4, respectively. Deviation was over 3 mm in 24 patients. Movement of more than 3 mm was observed only in RP1 and RP3. In RP1, it was related to bite block use. Movement exceeding 3 mm was most frequently observed in RP3. Primary tumor and metastatic LN volume change were clinical factors related to the RP3 movement.

CONCLUSION

Planning target volume margin of 4 mm for neck LN level I, 3 mm for neck LN level II, 5 mm for neck LN level III, and 3 mm for neck LN level IV was required to include all movements of each LN level. In patients using bite block, changes in primary tumor volume, and metastatic LN volume were related to significant movement.

Radioprotective and Anticancer Efficacies of Ganoderma Lucidum in a Mouse Tumor Model

Background:

Radiation dose is limited by deleterious nontarget effects, such as immunosuppression, necessitating the development of safe radioprotectants. In this study, we examined the radioprotective and anticancer efficacies of the traditional medicinal mushroom Ganoderma lucidum (GL) in a mouse xenograft tumor model.

Methods:

An aqueous extract was prepared from raw GL and administered by intraperitoneal injection. For the assessment of antitumor efficacy, ICR mice were inoculated with Sarcoma 180 cells and tumor growth (size and weight) compared among control (no treatment), GL alone, radiation alone, and GL plus radiation groups. For the assessment of the protection of the immune system, ICR mice received whole-body irradiation at 2 Gy for 2 weeks or longer with or without intraperitoneal GL administration, and changes in leukocyte, lymphocyte, and monocyte counts were measured. To examine the antioxidant efficacy of GL, ICR mice received whole-body radiation at 2 Gy with or without GL and plasma antioxidant activity measured by the luminol method.

Results:

Finally, the effects of GL on T helper (CD4-positive) and natural killer (CD8-positive) cell numbers were measured in C57BL mice by flow cytometry. GL administration alone suppressed tumor growth and the tumor-associated increase in lymphocyte and monocyte numbers. In addition, GL enhanced plasma antioxidant activity as well as both helper and natural killer T cell numbers in the presence and absence of irradiation.

Conclusion:

Collectively, these results demonstrate the antitumor and radioprotective efficacies of GL, which are likely mediated by protection against oxidative stress and preservation of immune cell populations.

The Pattern of Care for Brain Metastasis from Breast Cancer over the Past 10 Years in Korea: A Multicenter Retrospective Study (KROG 16-12)

PURPOSE

We aimed to investigate manifestations and patterns of care for patients with brain metastasis (BM) from breast cancer (BC) and compared their overall survival (OS) from 2005 through 2014 in Korea.

MATERIALS AND METHODS

We retrospectively reviewed 600 BC patients with BM diagnosed between 2005 and 2014. The median follow-up duration was 12.5 months. We categorized the patients into three groups according to the year when BM was initially diagnosed (group I [2005-2008], 98 patients; group II [2009-2011], 200 patients; and group III [2012-2014], 302 patients).

RESULTS

Over time, the median age at BM diagnosis increased by 2.2 years (group I, 49.0 years; group II, 48.3 years; and group III, 51.2 years; p=0.008). The percentage of patients with extracranial metastasis was 73.5%, 83.5%, and 86.4% for group I, II, and III, respectively (p=0.011). The time interval between BC and BM was prolonged in patients with stage III primary BC (median, 2.4 to 3 years; p=0.029). As an initial brain-directed treatment, whole-brain radiotherapy alone decreased from 80.0% in 2005 to 41.1% in 2014. Meanwhile, stereotactic radiosurgery or fractionated stereotactic radiotherapy alone increased from 13.3% to 34.7% during the same period (p=0.005). The median OS for group I, II, and III was 15.6, 17.9, and 15.0 months, respectively, with no statistical significance.

CONCLUSION

The manifestations of BM from BC and the pattern of care have changed from 2005 to 2014 in Korea. However, the OS has remained relatively unchanged over the 10 years.

Low-Dose Radiotherapy Attenuates Experimental Autoimmune Arthritis by Inducing Apoptosis of Lymphocytes and Fibroblast-Like Synoviocytes

Low-dose radiotherapy (LDRT) has been explored as a treatment option for various inflammatory diseases; however, its application in the context of rheumatoid arthritis (RA) is lacking. This study aimed to elucidate the mechanism underlying LDRT-based treatment for RA and standardize it. LDRT reduced the total numbers of immune cells, but increased the apoptotic CD4+ T and B220+ B cells, in the draining lymph nodes of collagen induced arthritis and K/BxN models. In addition, it significantly reduced the severity of various pathological manifestations, including bone destruction, cartilage erosion, and swelling of hind limb ankle. Post-LDRT, the proportion of apoptotic CD4+ T and CD19+ B cells increased significantly in the PBMCs derived from human patients with RA. LDRT showed a similar effect in fibroblast-like synoviocytes as well. In conclusion, we report that LDRT induces apoptosis in immune cells and fibro-blast-like synoviocytes, contributing to attenuation of arthritis.

Assessment of deep learning-based auto-contouring on interobserver consistency in target volume and organs-at-risk delineation for breast cancer: Implications for RTQA program in a multi-institutional study

PURPOSE

To quantify interobserver variation (IOV) in target volume and organs-at-risk (OAR) contouring across 31 institutions in breast cancer cases and to explore the clinical utility of deep learning (DL)-based auto-contouring in reducing potential IOV.

METHODS AND MATERIALS

In phase 1, two breast cancer cases were randomly selected and distributed to multiple institutions for contouring six clinical target volumes (CTVs) and eight OAR. In Phase 2, auto-contour sets were generated using a previously published DL Breast segmentation model and were made available for all participants. The difference in IOV of submitted contours in phases 1 and 2 was investigated quantitatively using the Dice similarity coefficient (DSC) and Hausdorff distance (HD). The qualitative analysis involved using contour heat maps to visualize the extent and location of these variations and the required modification.

RESULTS

Over 800 pairwise comparisons were analysed for each structure in each case. Quantitative phase 2 metrics showed significant improvement in the mean DSC (from 0.69 to 0.77) and HD (from 34.9 to 17.9 mm). Quantitative analysis showed increased interobserver agreement in phase 2, specifically for CTV structures (5-19 %), leading to fewer manual adjustments. Underlying IOV differences causes were reported using a questionnaire and hierarchical clustering analysis based on the volume of CTVs.

CONCLUSION

DL-based auto-contours improved the contour agreement for OARs and CTVs significantly, both qualitatively and quantitatively, suggesting its potential role in minimizing radiation therapy protocol deviation.

Development and Evaluation of the Utility of a Respiratory Monitoring and Visual Feedback System for Radiotherapy Using Machine Vision Technology

Background: We developed a machine vision technology program that tracks patients’ realtime breathing and automatically analyzes their breathing patterns.Materials and Methods: To evaluate its potential for clinical application, the image tracking performance and accuracy of the program were analyzed using a respiratory motion phantom. Changes in the stability and regularity of breathing were observed in healthy adult volunteers according to whether the breathing pattern mirrored the breathing guidance.Results and Discussion: Displacement within a few millimeters was observed in real-time with a clear resolution, and the image tracking ability was excellent. This result was consistent even in the sections where breathing patterns changed rapidly. In addition, the respiratory gating method that reflected the individual breathing patterns improved breathing stability and regularity in all volunteers.Conclusion: The findings of this study suggest that this technology can be used to set the appropriate window and the range of internal target volume by reflecting the patient’s breathing pattern during radiotherapy planning. However, further studies in clinical populations are required to validate this technology.

Comprehensive Analysis of Set-Up Gain of 6-Dimensional Cone-Beam CT Correction Method in Radiotherapy for Head and Neck and Brain Tumors

This study quantitatively analyzed the gain of the six-dimensional (6D) cone-beam CT (CBCT) correction method compared with the conventional set-up method in 60 patients who underwent radiation treatment of head and neck and brain tumors. The correction gain of CBCT was calculated for the translational and rotational motion components separately and in combination to evaluate the individual and overall effects of these motion components. Using a statistical simulation mimicking the actual set-up correction process, the effective gain of periodic CBCT correction during the entire treatment fraction was analyzed by target size and CBCT correction period under two different correction scenarios: translation alone and full 6D corrections. From the analyses performed in this study, the gain of CBCT correction was quantitatively determined for each situation, and the appropriate CBCT correction strategy was suggested based on treatment purpose and target size.

Prostate-Specific Antigen (PSA) Bounces Following Stereotactic Body Radiotherapy for Prostate Cancer: Importance of PSA Test Frequency

PURPOSE

Prostate-specific antigen (PSA) bounce is a common phenomenon that can be observed in patients of prostate cancer treated by radiotherapy. However, the clinical, pathological, or dosimetric predictors and clinical significance of PSA bounce in stereotactic body radiotherapy (SBRT) patients is still unknown.

METHODS

Between August 2006 to December 2015, 74 prostate cancer patients were treated by SBRT with Cyberknife at two medical centers. The prescription dose was 35-37.5 Gy in 5 fractions. Follow-up PSA tests were more frequently performed in one hospital than the other (median 4 vs. 10 times for initial one year). PSA bounce was defined as a rise of 0.2 ng/mL followed by a decline to or below the previous nadir.

RESULTS

A total of 74 patients, PSA bounce was observed in 41 patients (55.4%). On univariate analysis, the treated medical center (p = 0.02), PSA follow-up frequency (p = 0.01), patient age (p < 0.01), and total prescription dose (p = 0.03) were significant clinical factors in predicting the incidence of PSA bounce, while in multivariable analysis only the PSA follow-up frequency, and patient age remains significant.

CONCLUSION

PSA bounce was seen in a significant proportion of patients after Cyberknife SBRT. The PSA follow- up test frequency, and patient age were significant factors that were correlated with the incidence of PSA bounces in this study.

Effects of Vitamin E on the immune system and tumor growth during radiotherapy

PURPOSE

The purpose of this study is to evaluate the effects of Vitamin E (VE) on the immune system and tumor growth during radiotherapy (RT) in mice model.

METHODS

C57BL/6NCrSlc mice were randomly distributed in four groups (control, VE alone, RT alone, and VE + RT). In the VE and VE + RT groups, VE was administered in the diet at 500 mg/kg. Radiation was delivered at 2 Gy in a single fraction on the whole body or at 6 Gy in three fractions locally in the RT and VE + RT groups. Changes in leukocytes and T lymphocytes were counted and compared between the four groups. To evaluate the effects on tumor growth, Ehrlich carcinoma cells were injected into the thighs of mice, and tumor volumes and growth inhibition rates were compared.

RESULTS

The number of leukocytes was increased in the VE group compared with that in the control group. The magnitude of leukocyte recovery after RT was also increased by VE. This change was affected largely by alterations in lymphocytes and monocytes rather than that in granulocytes. Both CD4+ and CD8+ T lymphocytes were positively affected by VE. The tumor growth was inhibited not only by RT but also by VE alone. If RT was delivered with VE, tumor growth was markedly inhibited.

CONCLUSION

VE could increase the number of leukocytes, primarily lymphocytes, even after RT was delivered. VE also inhibited the tumor growth in addition to RT. Thus, VE may be a useful radioprotective supplement in radiotherapy without inducing tumor growth.