Correlation of Integral Dose, White Blood Cell Counts, and Radiation Therapy Techniques for Head and Neck Cancer Patients Under Radiation Therapy

Abstract

Purpose/Objective(s)Preclinical and some anecdotal clinical studies have shown that immunotherapy and radiation therapy may have a synergy, and immune-modulation during radiation therapy may play an important role in cancer treatment. The immune system is adversely impacted during radiation therapy due to radiation dose delivered outside the target. We hypothesize that the integral dose (ID) is directly correlated with a decline in the immune system as represented by a decline in the WBC count. The purpose of this study is to investigate the correlation of ID to the white blood cells (WBC) as well as to the radiation therapy techniques, such as Intensity Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT),Materials/MethodsAs a pilot study, 30 head and neck patients who received IMRT or VMAT were included in this retrospective study. These patients had either 3 arcs of VMAT treatment or 9-fields of IMRT treatment. These patients had a baseline WBC obtained prior to treatment, and 3 sets of labs drawn during the course of radiation treatment. The WBC reduction due to radiation treatment was determined for each patient. The ID was also calculated for each patient. The ID, WBC reduction, and treatment technique (IMRT or VMAT), were compared and analyzed.ResultsThe Integral dose has significant correlation with reduced WBC count during RT after controlling for concurrent chemotherapy (R square = 0.56, p = 0.008). When comparing the ID from 9-fields IMRT plans for and 3-Arc VMAT, the patients (n = 21) treated with VMAT plan had significantly higher ID compared to patients (n = 9) treated with IMRT plan. The mean ID was 16.4 Gy for VMAT and 13.0 Gy for IMRT with a p-value of 0.006.ConclusionsLower WBC counts during RT were associated with higher Integral doses even when controlling for concurrent chemotherapy. Although IMRT and VMAT can deliver higher conformity of radiation doses to targets, however, these benefits are achieved generally at the cost of greater integral doses to normal tissue. This study is ongoing in our Institution to exam the impact of integral doses and white cell count on overall survival. Purpose/Objective(s)Preclinical and some anecdotal clinical studies have shown that immunotherapy and radiation therapy may have a synergy, and immune-modulation during radiation therapy may play an important role in cancer treatment. The immune system is adversely impacted during radiation therapy due to radiation dose delivered outside the target. We hypothesize that the integral dose (ID) is directly correlated with a decline in the immune system as represented by a decline in the WBC count. The purpose of this study is to investigate the correlation of ID to the white blood cells (WBC) as well as to the radiation therapy techniques, such as Intensity Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT), Preclinical and some anecdotal clinical studies have shown that immunotherapy and radiation therapy may have a synergy, and immune-modulation during radiation therapy may play an important role in cancer treatment. The immune system is adversely impacted during radiation therapy due to radiation dose delivered outside the target. We hypothesize that the integral dose (ID) is directly correlated with a decline in the immune system as represented by a decline in the WBC count. The purpose of this study is to investigate the correlation of ID to the white blood cells (WBC) as well as to the radiation therapy techniques, such as Intensity Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT), Materials/MethodsAs a pilot study, 30 head and neck patients who received IMRT or VMAT were included in this retrospective study. These patients had either 3 arcs of VMAT treatment or 9-fields of IMRT treatment. These patients had a baseline WBC obtained prior to treatment, and 3 sets of labs drawn during the course of radiation treatment. The WBC reduction due to radiation treatment was determined for each patient. The ID was also calculated for each patient. The ID, WBC reduction, and treatment technique (IMRT or VMAT), were compared and analyzed. As a pilot study, 30 head and neck patients who received IMRT or VMAT were included in this retrospective study. These patients had either 3 arcs of VMAT treatment or 9-fields of IMRT treatment. These patients had a baseline WBC obtained prior to treatment, and 3 sets of labs drawn during the course of radiation treatment. The WBC reduction due to radiation treatment was determined for each patient. The ID was also calculated for each patient. The ID, WBC reduction, and treatment technique (IMRT or VMAT), were compared and analyzed. ResultsThe Integral dose has significant correlation with reduced WBC count during RT after controlling for concurrent chemotherapy (R square = 0.56, p = 0.008). When comparing the ID from 9-fields IMRT plans for and 3-Arc VMAT, the patients (n = 21) treated with VMAT plan had significantly higher ID compared to patients (n = 9) treated with IMRT plan. The mean ID was 16.4 Gy for VMAT and 13.0 Gy for IMRT with a p-value of 0.006. The Integral dose has significant correlation with reduced WBC count during RT after controlling for concurrent chemotherapy (R square = 0.56, p = 0.008). When comparing the ID from 9-fields IMRT plans for and 3-Arc VMAT, the patients (n = 21) treated with VMAT plan had significantly higher ID compared to patients (n = 9) treated with IMRT plan. The mean ID was 16.4 Gy for VMAT and 13.0 Gy for IMRT with a p-value of 0.006. ConclusionsLower WBC counts during RT were associated with higher Integral doses even when controlling for concurrent chemotherapy. Although IMRT and VMAT can deliver higher conformity of radiation doses to targets, however, these benefits are achieved generally at the cost of greater integral doses to normal tissue. This study is ongoing in our Institution to exam the impact of integral doses and white cell count on overall survival. Lower WBC counts during RT were associated with higher Integral doses even when controlling for concurrent chemotherapy. Although IMRT and VMAT can deliver higher conformity of radiation doses to targets, however, these benefits are achieved generally at the cost of greater integral doses to normal tissue. This study is ongoing in our Institution to exam the impact of integral doses and white cell count on overall survival.