- Email: [email protected]
SP-0493 THE BATTLE AGAINST NASOPHARYNGEAL CANCER
S198
ESTRO 31
reduced when considering the second part of the treatment (range:1.2-2.3 mm for both reference). Most of these reductions were statistically significant (Sup-ant/right/left; Inf-post/left, p<0.05).
Conclusions: Local 3D changes of rectal shape show an anisotropic motion of rectum and a large systematic component when taking the 1st fraction as reference, largely reduced when considering the second part of the treatment. Also the random motion is significantly reduced when considering the second part compared to the whole treatment. These results confirm that adaptive strategies aimed to concomitantly escalate the dose to the residual GTV in the last part of the treatment would benefit of reduced rectal motion (and, consequently, reduced margins) in addition to the possible tumor shrinkage. PD-0492 SEROMA VOLUME CHANGE AS AN INDICATOR FOR THE NEED OF REPLANNING DURING ADAPTIVE RT OF BREAST CANCER G. Franssen1, T. Alderliesten1, Z. van Kesteren2, P. Elkhuizen3, S. Conijn3, A. Duijn3, T. Janssen3, P. Remeijer3, C. van VlietVroegindeweij3 1 The Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Radiotherapy, Amsterdam, The Netherlands 2 AMC, Radiotherapy, Amsterdam, The Netherlands; 3 The Netherlands Cancer Institute – Antoni van Leeuwenhoek Hospital, Radiotherapy, Amsterdam, The Netherlands Purpose/Objective: In the course of radiotherapy (RT) of breast cancer patients with seroma development after breast-conserving surgery (BCS), the seroma volume may shrink considerably. This leads to an excess of unwanted healthy tissue irradiation. Each 100 cc increase in irradiated boost volume is associated with a fourfold increase in risk of fibrosis. Our present adaptive radiotherapy protocol, with replanning during the radiotherapy course, mitigates this problem. However, since seroma reduction differs per patient, replanning is not always necessary. The presently used selection criterion for the decision to enter the adaptive protocol is an initial seroma volume of at least 40 cc. The purpose of this work is to investigate whether the change of seroma volume is a good additional indicator for the need of replanning. Materials and Methods: 33 patients who developed seroma after BCS were selected for the study, all receiving a simultaneous integrated boost treatment with either 50.7 Gy (elective area) and 64.4 Gy (boost) in 28 fractions (12 patients) or 46.2 Gy (elective area) and 55.9 Gy (boost) in 21 fractions (21 patients). Initial seroma volume was measured on the planning CT (pCT). Seroma volume changes were evaluated on a repeat CT (rCT) after 13 of 28 or 9 of 21 fractions. A difference in irradiated healthy tissue volume (ΔVhealthy tissue) of 50 cc between pCT and rCT was selected as the clinically relevant threshold for replanning. The reliability of three seroma-based anatomical surrogates for ΔVhealthy tissue was investigated: 1. ΔVtumor bed: difference in tumor bed volume; 2. ΔVseroma: difference in seroma volume; 3. ΔVseroma, box: difference in volume of the encompassing box around the seroma. These surrogates are consecutively easier to obtain in a clinical setting, but at the same time they are likely to become less accurate surrogates of the irradiated healthy tissue volume. Results: The three surrogates for ΔVhealthy tissue were analyzed in terms of a binary classifier. Receiver operating characteristic (ROC) curves are displayed in the figure. It can be observed that (for the indicated operating points) ΔVtumor bed and ΔVseroma have false positive rates (FPRs) of, respectively, 0.44 and 0.78 for true positive rates (TPRs) of, respectively, 0.86 and 0.89. Areas-under-the-curve are 0.76 and 0.54, respectively. The operating points correspond with a threshold value of 20 cc. ΔVseroma, box has even higher FPRs, paired with lower TPRs.
Conclusions: ΔVtumor bed and ΔVseroma as surrogates of ΔVhealthy tissue have, respectievly, a moderate and poor predictive value concerning the effect of replanning on the irradiated healthy tissue volume of breast cancer patients with seroma, with high FPRs for acceptable TPRs. Furthermore, the encompassing box is markedly unreliable as a surrogate. We conclude that there is no clinical incentive to include seroma-based surrogates of ΔVhealthy tissue in the present adaptive protocol.
HONORARY MEMBERS MEMBERS LECTURES
LECTURES:
HONORARY
SP-0493 THE BATTLE AGAINST NASOPHARYNGEAL CANCER A. Lee1 1 Pamela Youde Nethersole Eastern Hospital, Clinical Oncology, Hong Kong, Hong Kong (SAR) China Nasopharyngeal cancer (NPC) is one of most difficult cancers to treat because of its highly malignant natural behavior and its anatomical proximity to critical structures. This cancer was invariably lethal before the advent of megavoltage radiotherapy (RT). Dr John Ho from Hong Kong was the leading pioneer in the battle against NPC. His foresight in identification of environmental carcinogens, the need for accurate prognostication by customized staging system, and the design of radiotherapy technique set the foundation for our understanding of this peculiar disease. Over the past 30 years, clinical oncologists from Hong Kong have made concerted efforts to continue this pursue. The statistics from the Hong Kong Cancer Registry from 1980 to 2009 showed that the agestandardized incidence rate of NPC has decreased by 51% for male and 59% for female populations. Together with improving treatment results, the corresponding age-standardized mortality rate has decreased by 60% and 67%, respectively. With advances of the technology of both diagnostic imaging and RT, together with development of concurrent cisplatin-based chemotherapy for locoregionally advanced NPC, retrospective analyses of 1374 consecutive patients treated at our institute (Pamela Youde Nethersole Eastern Hospital) from 1994 to 2007 showed significant improvement in cancer-specific survival from 79% in the era of 2-dimensional conventional RT, 81% in the era of 3-dimensional conformal RT, to 88% in the recent era of intensity-modulated RT. We have indeed achieved gratifying progress in this difficult battle against NPC, but there is no ground for complacency. Many serious problems remain to be solved: this cancer remains one of the most prevalent cancers in South East Asia, majority of patients still present with advanced disease, distant failure remains a key failure despite chemotherapy, late toxicities still seriously affects survivors’ quality of life. Furthermore, more accurate prognostic and predictive factors are needed for working towards the ideal goal of personalized medicine. Concerted efforts by all are needed to realize the dream of controlling this nasty cancer within our life time. SP-0494 RADIATION CAN BE A SURGEONS BEST TOOL P. Naredi1 1 Umeå University, Surgery, Umeå, Sweden In the era of multidisciplinary treatment and individualized care of the cancer patient, there is much focus on discoveries in basic biology
ESTRO 31
reduced when considering the second part of the treatment (range:1.2-2.3 mm for both reference). Most of these reductions were statistically significant (Sup-ant/right/left; Inf-post/left, p<0.05).
Conclusions: Local 3D changes of rectal shape show an anisotropic motion of rectum and a large systematic component when taking the 1st fraction as reference, largely reduced when considering the second part of the treatment. Also the random motion is significantly reduced when considering the second part compared to the whole treatment. These results confirm that adaptive strategies aimed to concomitantly escalate the dose to the residual GTV in the last part of the treatment would benefit of reduced rectal motion (and, consequently, reduced margins) in addition to the possible tumor shrinkage. PD-0492 SEROMA VOLUME CHANGE AS AN INDICATOR FOR THE NEED OF REPLANNING DURING ADAPTIVE RT OF BREAST CANCER G. Franssen1, T. Alderliesten1, Z. van Kesteren2, P. Elkhuizen3, S. Conijn3, A. Duijn3, T. Janssen3, P. Remeijer3, C. van VlietVroegindeweij3 1 The Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Radiotherapy, Amsterdam, The Netherlands 2 AMC, Radiotherapy, Amsterdam, The Netherlands; 3 The Netherlands Cancer Institute – Antoni van Leeuwenhoek Hospital, Radiotherapy, Amsterdam, The Netherlands Purpose/Objective: In the course of radiotherapy (RT) of breast cancer patients with seroma development after breast-conserving surgery (BCS), the seroma volume may shrink considerably. This leads to an excess of unwanted healthy tissue irradiation. Each 100 cc increase in irradiated boost volume is associated with a fourfold increase in risk of fibrosis. Our present adaptive radiotherapy protocol, with replanning during the radiotherapy course, mitigates this problem. However, since seroma reduction differs per patient, replanning is not always necessary. The presently used selection criterion for the decision to enter the adaptive protocol is an initial seroma volume of at least 40 cc. The purpose of this work is to investigate whether the change of seroma volume is a good additional indicator for the need of replanning. Materials and Methods: 33 patients who developed seroma after BCS were selected for the study, all receiving a simultaneous integrated boost treatment with either 50.7 Gy (elective area) and 64.4 Gy (boost) in 28 fractions (12 patients) or 46.2 Gy (elective area) and 55.9 Gy (boost) in 21 fractions (21 patients). Initial seroma volume was measured on the planning CT (pCT). Seroma volume changes were evaluated on a repeat CT (rCT) after 13 of 28 or 9 of 21 fractions. A difference in irradiated healthy tissue volume (ΔVhealthy tissue) of 50 cc between pCT and rCT was selected as the clinically relevant threshold for replanning. The reliability of three seroma-based anatomical surrogates for ΔVhealthy tissue was investigated: 1. ΔVtumor bed: difference in tumor bed volume; 2. ΔVseroma: difference in seroma volume; 3. ΔVseroma, box: difference in volume of the encompassing box around the seroma. These surrogates are consecutively easier to obtain in a clinical setting, but at the same time they are likely to become less accurate surrogates of the irradiated healthy tissue volume. Results: The three surrogates for ΔVhealthy tissue were analyzed in terms of a binary classifier. Receiver operating characteristic (ROC) curves are displayed in the figure. It can be observed that (for the indicated operating points) ΔVtumor bed and ΔVseroma have false positive rates (FPRs) of, respectively, 0.44 and 0.78 for true positive rates (TPRs) of, respectively, 0.86 and 0.89. Areas-under-the-curve are 0.76 and 0.54, respectively. The operating points correspond with a threshold value of 20 cc. ΔVseroma, box has even higher FPRs, paired with lower TPRs.
Conclusions: ΔVtumor bed and ΔVseroma as surrogates of ΔVhealthy tissue have, respectievly, a moderate and poor predictive value concerning the effect of replanning on the irradiated healthy tissue volume of breast cancer patients with seroma, with high FPRs for acceptable TPRs. Furthermore, the encompassing box is markedly unreliable as a surrogate. We conclude that there is no clinical incentive to include seroma-based surrogates of ΔVhealthy tissue in the present adaptive protocol.
HONORARY MEMBERS MEMBERS LECTURES
LECTURES:
HONORARY
SP-0493 THE BATTLE AGAINST NASOPHARYNGEAL CANCER A. Lee1 1 Pamela Youde Nethersole Eastern Hospital, Clinical Oncology, Hong Kong, Hong Kong (SAR) China Nasopharyngeal cancer (NPC) is one of most difficult cancers to treat because of its highly malignant natural behavior and its anatomical proximity to critical structures. This cancer was invariably lethal before the advent of megavoltage radiotherapy (RT). Dr John Ho from Hong Kong was the leading pioneer in the battle against NPC. His foresight in identification of environmental carcinogens, the need for accurate prognostication by customized staging system, and the design of radiotherapy technique set the foundation for our understanding of this peculiar disease. Over the past 30 years, clinical oncologists from Hong Kong have made concerted efforts to continue this pursue. The statistics from the Hong Kong Cancer Registry from 1980 to 2009 showed that the agestandardized incidence rate of NPC has decreased by 51% for male and 59% for female populations. Together with improving treatment results, the corresponding age-standardized mortality rate has decreased by 60% and 67%, respectively. With advances of the technology of both diagnostic imaging and RT, together with development of concurrent cisplatin-based chemotherapy for locoregionally advanced NPC, retrospective analyses of 1374 consecutive patients treated at our institute (Pamela Youde Nethersole Eastern Hospital) from 1994 to 2007 showed significant improvement in cancer-specific survival from 79% in the era of 2-dimensional conventional RT, 81% in the era of 3-dimensional conformal RT, to 88% in the recent era of intensity-modulated RT. We have indeed achieved gratifying progress in this difficult battle against NPC, but there is no ground for complacency. Many serious problems remain to be solved: this cancer remains one of the most prevalent cancers in South East Asia, majority of patients still present with advanced disease, distant failure remains a key failure despite chemotherapy, late toxicities still seriously affects survivors’ quality of life. Furthermore, more accurate prognostic and predictive factors are needed for working towards the ideal goal of personalized medicine. Concerted efforts by all are needed to realize the dream of controlling this nasty cancer within our life time. SP-0494 RADIATION CAN BE A SURGEONS BEST TOOL P. Naredi1 1 Umeå University, Surgery, Umeå, Sweden In the era of multidisciplinary treatment and individualized care of the cancer patient, there is much focus on discoveries in basic biology