Treatment of Thymoma and Thymic Carcinoma with Proton Beam Therapy: Outcomes from the Proton Collaborative Group Prospective Registry

PURPOSE/OBJECTIVE(S)

Given the generally long natural history of thymic malignancies, proton beam therapy (PBT) is advocated to minimize the risk of long-term toxicities to mediastinal organs. Adverse events (AE) and long-term clinical outcomes for this population have not been well-characterized.

MATERIALS/METHODS

The Proton Collaborative Group registry (NCT01255748), a multi-institutional prospective database of academic and community proton centers in the US, was queried for patients with thymomas and thymic carcinomas treated with PBT. Patients with recurrent/metastatic disease, non-thymic histology, received either prior or palliative radiotherapy (dose < 40 Gy RBE) were excluded. Overall survival (OS) and local control (LC) were estimated using Kaplan-Meier methods.

RESULTS

A total of 97 patients were identified in the PCG registry. After applying relevant exclusion criteria, 70 patients from 12 proton centers treated from 2011-2021 were included for analysis. Median follow-up length was 16 months. Median age was 58.5 years (IQR 46-63), and 60% were female. 81.4% had a diagnosis of thymoma, and 18.6% thymic carcinoma. 59 patients underwent surgical resection. 11 were treated with definitive PBT, of which 5 received concurrent chemotherapy. Median dose was 54 Gy RBE (range 41.4 - 70 Gy RBE), median number of fractions was 30 (range 21 - 38). 73.4% received pencil beam scanning and 23% uniform scanning PBT. Treatment was overall well-tolerated: a single patient developed grade 4 pneumonitis. Grade 3 AEs were seen in 3 patients - dyspnea, anorexia, and heart failure. Highest grade toxicity experienced was grade 2 for 47.1% and grade 1 for 42.9% of patients. 3-year overall survival (OS) was 82.6% for the entire cohort. 3-year OS was 94% for resected/adjuvant cohort and 35.6% in the non-surgical/definitive cohort. 3-year local control (LC) was 91.7% for the entire cohort. By surgery/margin status, 3-year LC was 96.8% in patients with close or negative margins (a single failure in a patient with close margins), whereas 3-year LC was 55.1% for patients with positive margins/unresectable disease.

CONCLUSION

Thymic malignancies treated with PBT appear to have favorable outcomes, especially in the adjuvant setting, in this cohort representing the largest series of such patients.

Oxidative stress in oral diseases

Oxidative species, including reactive oxygen species (ROS), are components of normal cellular metabolism and are required for intracellular processes as varied as proliferation, signal transduction, and apoptosis. In the situation of chronic oxidative stress, however, ROS contribute to various pathophysiologies and are involved in multiple stages of carcinogenesis. In head and neck cancers specifically, many common risk factors contribute to carcinogenesis via ROS-based mechanisms, including tobacco, areca quid, alcohol, and viruses. Given their widespread influence on the process of carcinogenesis, ROS and their related pathways are attractive targets for intervention. The effects of radiation therapy, a central component of treatment for nearly all head and neck cancers, can also be altered via interfering with oxidative pathways. These pathways are also relevant to the development of many benign oral diseases. In this review, we outline how ROS contribute to pathophysiology with a focus toward head and neck cancers and benign oral diseases, describing potential targets and pathways for intervention that exploit the role of oxidative species in these pathologic processes.

Abstract P2-11-13: The Effect of Positive Axillary Lymph Nodes on Symptoms, Physical Impairments, and Function

Purpose/Objective(s): The role of axillary lymph node (ALN) sampling in breast cancer (BC) treatment continues to evolve, and BC patients are recommended for post-operative regional nodal radiation therapy (RNRT) based on the number of positive ALN. RNRT is recommended for patients with 4 or more positive ALN, but it remains controversial in patients with 1–3 positive ALN and is rarely recommended for patients without positive ALN. Consideration of anticipated functional impairments often guides decision making. The purpose of this analysis is to investigate functional impairments in BC patients with varying numbers of positive ALN.

Materials/Methods: 166 women were diagnosed with BC between 2001–05 and enrolled and treated in a prospective surveillance physical therapy program. 110 had zero positive ALN, 37 had 1–3 positive ALN, and 19 had 4 or more positive ALN on either sentinel LN biopsy or ALN dissection. Participants' upper extremity (UE) range of motion, strength, and limb volume were assessed pre-operatively and at 1, 3, 6, 9, and 12+ months post-operatively by a physical therapist. Limb volume was assessed using infrared optoelectronic perometry. At 12+ months, overall health status, UE symptoms and function, and physical activity levels were reported using standardized questionnaires. Chi-square tests and one-way ANOVA analyses were used to determine significance between groups (p ≤ 0.05).

Results: Of these 166 patients, 94 received mastectomy and 72 received lumpectomy, while 41 received RNRT and 58 received whole breast tangent RT. No significant differences were found between groups with regard to age or race. The number of dissected LN was not significantly different between those patients with 1–3 positive ALN and 4 or more positive ALN. Rates of lymphedema and seroma were not significantly different between those patients with zero positive ALN and 1–3 positive ALN, and rates of cording were not significantly different between any of the groups. Increased lymphedema (p = 0.03) and seroma (p = 0.005) were seen in those patients with 4 or more positive ALN compared to those patients with zero positive ALN, but this may also be related to a significantly greater number of dissected LN in the former group. By 12+ months post-operatively, there were no differences in shoulder abduction, shoulder flexion, internal rotation, or external rotation between groups. No differences were seen between groups in self-reported fatigue, UE swelling or weakness, arm stiffness, or ability to climb stairs.

Conclusions: Functional impairments represent an important category of morbidity for BC survivors and should be considered in pre-treatment decision making. The number of positive ALN may not correlate with increased impairment over the first year of treatment when a prospective surveillance physical therapy program is part of the plan of care. Additional research is needed to assess longer-term changes and the impact of axillary surgery and/or radiation in the context of aggregate effects of other BC treatment modalities.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-11-13.

Abstract P2-11-14: Symptoms, Physical Impairments, and Function in Breast Cancer Patients with Negative Axillary Lymph Nodes

Purpose/Objective(s): Breast cancer (BC) patients are recommended for post-operative regional nodal radiation therapy (RNRT) based on the number of positive axillary lymph nodes (LN). While RNRT is recommended for patients with 4 or more positive LN, it remains controversial in patients with 1–3 positive LN. For these patients, consideration of anticipated functional impairments often guides decision making, but these considerations are confounded by the inseparable effects of disease in and treatment of the axilla. The purpose of this analysis is to investigate the effect of various therapies on functional impairments in BC patients without axillary disease.

Materials/Methods: 166 women were diagnosed with BC between 2001–05 and enrolled and treated in a prospective surveillance physical therapy program. 110 had zero positive axillary LN on either sentinel LN biopsy or axillary LN dissection and were analyzed for this report. Participants' upper extremity (UE) range of motion, strength, and limb volume were assessed pre-operatively and at 1, 3, 6, 9, and 12+ months post-operatively by a physical therapist. Limb volume was assessed using infrared optoelectronic perometry. At 12+ months, overall health status, UE symptoms and function, and physical activity levels were reported using standardized questionnaires. Chi-square tests and one-way ANOVA analyses were used to determine significance between groups (p ≤ 0.05).

Results: Of these 110 patients, 34 received mastectomy without RT, 21 received mastectomy with RNRT, 10 received lumpectomy alone, and 45 received lumpectomy with whole breast tangent RT. No significant differences were found between groups with regard to stage, ER/PR status, and number of dissected LN. Rates of lymphedema, cording, and seroma were not significantly different between groups. By 12+ months post-operatively, there were no differences in shoulder abduction, shoulder flexion, internal rotation, or external rotation between groups. No differences were seen between groups in self-reported fatigue, UE swelling or weakness, arm stiffness, or ability to climb stairs.

Conclusions: Functional impairments represent an important category of morbidity for BC survivors and should be considered in pre-treatment decision making. In patients without axillary disease, post-operative RNRT or whole breast tangent RT may not contribute significantly to impairment over the first year of treatment when a prospective surveillance physical therapy program is part of the plan of care. Additional research is needed to assess longer-term changes and the impact of radiation in the context of the aggregate effect of disease burden combined with other BC treatment modalities.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-11-14.

Long-term follow-up of prostate cancer patients treated with vaccine and definitive radiation therapy

BACKGROUND

Vaccine therapy in combination with radiation therapy may improve distant and/or local control in prostate cancer. We present long-term follow-up data on the secondary and exploratory endpoints of safety and biochemical failure, respectively, from patients with clinically localized prostate cancer treated definitively with a poxviral vector-based therapeutic vaccine combined with external beam radiation therapy (EBRT).

METHODS

Thirty-six prostate cancer patients received definitive EBRT plus vaccine. A total of 18 patients were treated with adjuvant standard-dose interleukin-2 (S-IL-2) (4 MIU m(-2)) and 18 were treated with very low-dose IL-2 (M-IL-2) (0.6 MIU m(-2)). Seven patients were treated with EBRT alone. Twenty-six patients treated with EBRT plus vaccine returned for follow-up, and we reviewed the most recent labs and clinical notes of the remaining patients.

RESULTS

Median follow-up for the S-IL-2, M-IL-2 and EBRT-alone groups was 98, 76 and 79 months, respectively. Actuarial 5-year PSA failure-free probability was 78%, 82% and 86% (P=0.58 overall), respectively. There were no significant differences between the actuarial overall survival and the prostate cancer-specific survival between the two vaccine arms. Of the 26 patients who returned for follow-up, Radiation Therapy Oncology Group grade ≥2 genitourinary (GU) and gastrointestinal (GI) toxicity was seen in 19% and 8%, respectively, with no difference between the arms (P=1.00 and P=0.48 for grade ≥2 GU and GI toxicity, respectively). In all, 12 patients were evaluated for PSA-specific immune responses, and 1 demonstrated a response 66 months post-enrollment.

CONCLUSIONS

We demonstrate that vaccine combined with EBRT does not appear to have significant differences with regard to PSA control or late-term toxicity compared with standard treatment. We also found limited evidence of long-term immune response following vaccine therapy.

PD02-03: The Effect of Breast Conservation Therapy vs Mastectomy on Symptoms, Physical Impairments, and Function

Background: Early-stage breast cancer (BC) patients choose between breast conservation therapy (BCT) and mastectomy based on comparable recurrence rates and overall survival. In the absence of mortality benefit, consideration of anticipated functional impairments could guide decision making. Although BCT offers less extensive surgery, the administration of radiation therapy (RT) may adversely impact upper extremity (UE) function. The purpose of this analysis is to investigate the effect of BCT vs modified radical mastectomy (MRM) without RT on functional impairments among BC survivors.

Materials and Methods: 196 women diagnosed with BC between 200105 were enrolled and treated in a prospective surveillance physical therapy program. 115 received either BCT, including lumpectomy and whole breast RT, or MRM without RT and were analyzed for this report. Participants’ UE range of motion (ROM), strength, and limb volume were assessed pre-operatively and at 1, 3, 6, 9, and 12+ months post-operatively by a physical therapist. Limb volume was assessed using infrared optoelectronic perometry. At 12+ months, overall health status, UE symptoms and function, and physical activity levels were reported using standardized questionnaires. Analysis of variance estimated differences in impairments and self-reported symptoms and function. One-way ANOVA analysis was used to determine significance between groups (p ≤ 0.05).

Results: 65 women (57.5%) received BCT and 50 women (42.5%) received MRM. No significant differences in age, BMI, stage, ER/PR status, and number of dissected lymph nodes were found between groups. At 1 month post-operatively, shoulder internal rotation (p=0.03), abduction (p=0.01), and flexion (p=0.004) were worse in post-MRM patients, with a trend towards worse external rotation (p=0.06). A higher rate of axillary cording was seen in patients post-MRM (p=0.02). By 12+ months post-operatively, there were no differences in any of the shoulder ROM variables. BCT patients reported, however, greater weakness (p=0.03) and diminished ability to perform heavy household tasks (p=0.03). There was no significant difference between BCT vs. MRM in rates of early lymphedema (40% vs 38%) or seroma (14% vs 22%).

Conclusion: Functional impairments represent an important category of morbidity for BC survivors and should be considered in pre-treatment decision making. Post-operative RT as part of BCT may not contribute significantly to impairment over the first year of treatment. The presence of self-reported weakness and difficulty performing heavy household tasks at 12+ months suggest possible future functional deficits, especially considering the potentially progressive nature of RT-associated tissue changes. Additional research is needed to assess longer-term changes and the impact of RT in the context of aggregate effects of other BC treatment modalities.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD02-03.