Locoregional Control Benefit of a Tumor Bed Boost for Ductal Carcinoma In Situ (DCIS)

PURPOSE/OBJECTIVE(S)

Radiotherapy (RT) following breast conserving surgery (BCS) for ductal carcinoma in situ (DCIS) reduces invasive and in situ recurrences. Whereas landmark studies suggest that a tumor bed boost improves local control for invasive breast cancer, the benefit in DCIS remains less certain. We evaluated outcomes of DCIS patients treated with or without a boost and hypothesized that a tumor bed boost would improve locoregional control rates.

MATERIALS/METHODS

The study cohort comprised patients with DCIS who underwent BCS at our institution from 2004-2018. Clinicopathologic features, treatment parameters and outcomes were ascertained from medical records. Patient and tumor characteristics were evaluated relative to outcomes using univariable and multivariable Cox models. Recurrence-free survival (RFS) estimates were generated using the Kaplan Meier method.

RESULTS

We identified 1675 patients who underwent BCS for DCIS (median age 56 [interquartile range (IQR) 49, 64]). Boost RT was employed in 68% of cases (n = 1146) and endocrine therapy in 32% (n = 536). At a median follow-up of 4.2 years (IQR 1.4, 7.0), we observed 61 locoregional recurrence events (56 local, 5 regional) and 21 deaths. Univariable logistic regression demonstrated that boost RT was more common among younger patients (p<0.001) with positive/close margins (p<0.001), and with larger tumors (p<0.001) of higher grade (p = 0.025). The 10-year RFS rate was 88.8% among those receiving a boost and 84.3% among those without a boost (p = 0.3), and neither univariable nor multivariable analyses revealed an association between boost RT and locoregional recurrence.

CONCLUSION

Among patients with DCIS who underwent BCS, use of a tumor bed boost was not associated with locoregional recurrence or RFS. Despite a preponderance of adverse features among the boost cohort, outcomes were similar to those not receiving a boost, suggesting that a boost may mitigate risk of recurrence among patients with high-risk features. Ongoing studies will elucidate the extent to which a tumor bed boost influences disease control rates.

Radiation in a New Era of Multiple Myeloma Management: Patterns of Utilization, Clinical, Radiologic, and Biochemical Outcomes, and Possible Genomic Correlates of Response

PURPOSE/OBJECTIVE(S)

Systemic therapies for multiple myeloma (MM) have advanced considerably, improving patient outcomes. Yet, the use of radiotherapy (RT) has remained heterogeneous, and even controversial, due to minimal data on outcomes. With the ultimate goal of guiding the design of prospective trials incorporating RT, we initiated a study of our institutional experience treating MM with RT since 1/1/2000. Here we report a preliminary feasibility analysis of an initial sample cohort, identifying patterns of RT utilization, outcomes, and impact of RT on radiographic and biochemical markers, with genomic characterization for more recently treated patients.

MATERIALS/METHODS

Five hundred six pathologically confirmed MM patients who received RT to 1190 sites between January 1, 2000, and June 1, 2022, were identified. Patient, disease, and treatment characteristics were analyzed for 50 consecutive patients treated in 2019 and tested for association with local and distant failure (LF, DF) using univariable and multivariable analysis. Genomic data was obtained via next generation sequencing using an institutional targeted sequencing panel.

RESULTS

Amongthe 50 patients analyzed (median 63 years), 90 lesions were treated with RT, 33% with concurrent systemic therapy, to median dose of 20 Gy (8-46 Gy) over a median of 5 fractions (1-25). RT Indications were pain (56%), critical structure involvement (25%), peri-operative (9%), salvage/consolidation (8%), and bridging therapy (2%). Median size of RT-treated lesions was 4.2 cm (1.4-7.9) and included non-vertebral bones (62%), spine (24%), and extramedullary sites (14%). The median number of lines of pre-RT therapy was 7 (1-14) and 51% had >9 lesions on imaging, 47% involving both medullary and extramedullary sites. With median follow-up of 12.4 months (0.5-46), LF occurred in 5% of treated sites and 89% had DF, most commonly in both medullary + extramedullary (51.4%) sites. Absolute decreases 1-week to 1-month post-RT were observed in % of marrow plasma cell (median 4.0%), M spike (0.30 g/dL), total protein (0.3 g/dL), K:L ratio (0.01), lesion size (1.5cm), and lesion SUV (3.1) but in this limited sample, none were significantly associated with disease control. A cohort of 62 RT-treated MM patients from 2016-2022 had genomic data available; most common tumor mutations were in TP53 (35%), HIST1 (34%), NRAS (34%), and KRAS (23%).

CONCLUSION

In this pilot analysis of a sampling cohort of RT-treated MM, we report on patterns of utilization, outcomes, and biochemical and radiographic correlates. At the meeting, we will present the full analysis of the >500 MM patients and further analyze emerging genomic data. We aim to characterize the role of RT in the modern era of systemic therapy to guide the design of future prospective trials and to inform novel approaches for incorporating RT into the treatment paradigm.

Prospective Evaluation of MRI-Based Endoluminal Brachytherapy with Novel Applicator for Anorectal Cancer

PURPOSE/OBJECTIVE(S)

To present results of patients treated on a prospective dose escalation trial of MRI-based endoluminal high dose rate (HDR) brachytherapy (BT) and concurrent chemotherapy utilizing a novel double-balloon applicator for recurrent or inoperable rectal and anal cancer.

MATERIALS/METHODS

A total of 15 patients were enrolled on a prospective, institutional review board-approved dose escalation protocol evaluating endoluminal HDR-BT with concurrent chemotherapy. Inclusion criteria were histologically confirmed locally residual or recurrent cancer of the rectum or anus and prior pelvic external beam radiation therapy (EBRT). BT was delivered with a novel anorectal applicator consisting of an inner balloon, which supported 8 channels for the radioactive source, and a compliant outer balloon for optimal deformation against exophytic lesions. Applicator insertion and treatment delivery were performed under general anesthesia in 3 weekly sessions. MRI-based treatment planning was performed while under anesthesia during the first session only. Capecitabine (825 mg/m2 BID) was administered Monday-Friday on the weeks of BT. Efficacy and toxicity were evaluated by clinical assessment and MRI examinations at pre-defined intervals (3, 6, and 12 months for the first year) after the procedure.

RESULTS

From 1/2015 to 4/2018 15 patients at a median age of 65 years (43-86) with recurrent or residual cancer (9 rectal, 6 anal) were enrolled and treated at the initial dose level of 15 Gy in 3 fractions (n = 6), the intermediate dose level of 18 Gy in 3 fractions (n = 3), and the highest dose level of 21 Gy in 3 fractions (n = 6). Treatment was delivered as planned for 14 patients; 1 patient was treated with a single-channel Bougie applicator for the third fraction due to the development of severe circumferential narrowing that prevented insertion of the endorectal applicator. On first MRI imaging post-BT, 7 patients had a complete response, 5 patients had a partial response, 1 patient had progressive disease, and 2 patients had indeterminate imaging. At a median follow up of 26 months (7-88), 10 patients (6 rectal and 4 anal) have developed a local recurrence (2 also with distant disease) which were treated with surgery (4), systemic therapy (1), or no known therapy (3). Acute (<6 months post-RT) grade 2 and 3 toxicities were observed in 1 (rectal bleeding) and 2 (anorectal pain) patients, respectively, and the only late grade 3 toxicity observed was rectal bleeding in 1 patient.

CONCLUSION

Endoluminal HDR BT with MRI-based treatment planning and a novel double-balloon applicator was feasible up to a dose level of 21Gy in 3 fractions in patients with non-operable rectal or anal cancers and history of prior EBRT. The clinical efficacy and toxicity associated with this treatment should be more clearly defined with analyses of larger cohorts of patients.

Pre-Brachytherapy Diffusion-Weighted Magnetic Resonance Imaging (DW-MRI) Response as Predictor of Local Control in the Definitive Treatment of Cervical Cancer

PURPOSE/OBJECTIVE(S)

Chemoradiation consisting of external beam radiotherapy (EBRT) followed by brachytherapy (BT) is the standard of care for Stage IB2-IVA cervical cancer (CC). Multi-parametric MRI (mpMRI) is a valuable tool for initial staging, treatment planning and response assessment. In this study, we aim to explore the potential of mpMRI, in particular DW-MRI, to predict overall tumor control following chemoradiation in CC.

MATERIALS/METHODS

We identified 78 consecutive patients treated with chemoradiation for FIGO IB2-IVA CC between 2012-2020, who had an MRI at baseline (MRb) and post-EBRT prior to brachytherapy boost (MRpb) that included DW-MRI (b-value = 0 and 800 s/mm2). Median age was 53 years, most patients had squamous cell carcinoma (76.9%) and advanced-stage disease (56.4% stage IIIA-IVA). Median time from completion of EBRT to MRpb was 3 days. Regions of interest (ROI) in primary tumor were delineated on DW image (b = 0 s/mm2) using ITK-SNAP software. DW-MRI data were fitted to a monoexponential model to calculate apparent diffusion coefficient (ADC) values using in-house software platform (MRI-QAMPER). MRpb mean ADC values (n = 78) and relative changes (%) in mean ADC values between MRb and MRpb (n = 64) were correlated with outcomes, including local failure (LF), regional or distant failure (RDF), and failure at any site (FAS), with death without failure as a competing risk. Median follow-up time was 45 months (95% CI 38, 53).

RESULTS

At first post treatment assessment, 72 patients (92.3%) had a complete response (CR) in the cervix and 68 patients (87.2%) had CR in all disease sites. Of patients who had CR in the cervix (n = 72), only 1 patient had local recurrence. Of patients who had CR in all disease sites, 10 later recurred (1 LF only, 1 LF&RDF, 8 RDF only). Overall, 7 patients (9%) had LF, and 19 patients (24.4%) had FAS. A higher mean ADC value in MRpb was associated with LF (HR 4.3, 95% CI 1.32, 14.6; P = 0.016), but not with RDF (P = 0.4) or FAS (P = 0.5). A higher relative change in the mean ADC value between MRb and MRpb was associated with a lower risk of LF (HR 0.94, 95% CI 0.90, 0.98; P = 0.002), but not with RDF (P = 0.8) or FAS (P = 0.4).

CONCLUSION

Treatment response as measured on prebrachytherapy DW-MRI is a significant predictor of local control in patients undergoing chemoradiation for stage IB2-IVA CC. ADC values, a quantitative imaging biomarker on MRpb may be instrumental in dose intensification/de-escalation efforts in CC.

Salvage Radiotherapy as a Bridge for Relapsed Secondary CNS Lymphoma

PURPOSE/OBJECTIVE(S)

Secondary CNS lymphoma (SCNSL) is a challenging clinical scenario observed in 2-5% of non-Hodgkin lymphoma patients, for which a standard of care has not been defined. We studied the indications for, and outcomes of SCNSL patients referred for radiotherapy (RT).

MATERIALS/METHODS

We identified patients with aggressive B cell lymphoma who received brain RT for SCNSL between 1999-2023 at a tertiary cancer center. Patients were grouped and analyzed by RT indication. Overall survival (OS) was determined from RT start using the Kaplan-Meier method. OS analysis comparing patients who did and did not receive therapy after RT was landmarked at 60 days from start of RT to minimize immortal time bias. "SCNSL-directed therapy" is defined as systemic therapy for the treatment of SCNSL, as opposed to CNS prophylaxis.

RESULTS

We identified 99 SCNSL patients treated with RT. To account for the heterogeneity of RT referrals, we focused on the most common indication: salvage of radiographic progression after SCNSL-directed systemic therapy (n = 58). Among this group, median age was 62 (interquartile range [IQR]: 48-69) and 86% had diffuse large B cell histology. At initial lymphoma diagnosis, 10% of patients had CNS involvement, 90% received Rituximab-based therapy, and 25% received prior CNS prophylaxis. For SCNSL directed therapy, 90% received methotrexate (MTX)-based regimen. Median time from initial SCNSL diagnosis to RT was 4.4 months (IQR 1.7-7.0), with a median of 2.0 lines of therapy prior to RT (IQR 1.0-3.0). 86% of patients were symptomatic at RT with median KPS of 70 (IQR: 60-80). RT targets included whole brain (86%) and partial brain (14%). 1 patient had craniospinal RT. Median RT dose was 30 Gy (IQR: 24-30) over 10 fractions. Median OS for the entire salvage cohort was 3.5 months (m). Landmark analysis 2m post RT showed that median OS differed when patients were stratified by receipt of further therapy: CAR-T (9.4m, n = 4), hematopoietic cell transplant (8.5m, n = 6), other systemic therapy (4.4m, n = 17), no systemic therapy (0.6m, n = 10) (p = 0.0004). 29% of patients who received further therapy after RT achieved long term survival.

CONCLUSION

In our cohort, most SCNSL patients are referred for salvage RT, with a median OS of 3.5m. 86% of patients had neurologic symptoms after having failed a median of 2 lines of SCNSL-directed therapy; the clinical urgency of this scenario implies that without RT, patients may not have been suitable candidates for further therapy. However, among patients for whom RT was successfully used to bridge to additional therapy, 29% could achieve long-term survival. This study supports further investigation of RT as a combined modality strategy for relapsed/refractory SCNSL, including with emerging cellular therapies.

Induction chemotherapy with docetaxel, cisplatin, fluorouracil, and leucovorin for squamous cell carcinoma of the head and neck: a phase I/II trial

PURPOSE

A phase I/II trial of docetaxel, cisplatin, fluorouracil (5-FU), and leucovorin (TPFL5) induction chemotherapy for patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN).

PATIENTS AND METHODS

Twenty-three previously untreated patients with stage III or IV SCCHN and Eastern Cooperative Oncology Group functional status less than or equal to 2 were treated with TPFL5. Postchemotherapy home support included intravenous fluids, prophylactic antibiotics, and granulocyte colony-stimulating factor (G-CSF). Docetaxel dose was escalated to determine the maximum-tolerated dose (MTD). Fifteen patients were treated with three cycles of TPFL5 at MTD. Patients who achieved either a partial response (PR) or complete response (CR) to three cycles of TPFL5 then received definitive twice-daily radiation therapy. Toxicity and clinical and pathologic response to TPFL5 were assessed.

RESULTS

Twenty-three patients received a total of 69 cycles of TPFL5. The MTD was determined to be docetaxel 60 mg/m2. Dose-limiting toxicity (DLT) was neutropenia. Additional significant toxicities at MTD were nausea, mucositis, diarrhea, peripheral neuropathy, and sodium-wasting nephropathy. The overall response rate to TPFL5 was 100%, which included 14 of 23 (61%) clinical CRs and nine of 23 (39%) clinical PRs. Primary-site clinical and pathologic CR rates were 19 of 22 (86%) CRs and 20 of 22 (91%) CRs, respectively. Eight patients had less than a CR in the neck to chemotherapy and, therefore, had postradiation neck dissections, four of which were positive for residual tumor.

CONCLUSION

TPFL5 is a tolerable induction regimen in patients with good performance status. The DLT is neutropenia with significant mucositis, diarrhea, peripheral neuropathy, and sodium-wasting nephropathy. The high response rates to TPFL5 justify further evaluation of this combination of agents in the context of formal clinical trials.

Selective expansion of 5,10-methylenetetrahydrofolate pools and modulation of 5-fluorouracil antitumor activity by leucovorin in vivo

Expansion of CH2THF pools in tissues of BALB/c mice bearing s.c.-implanted EMT6 mammary adenocarcinomas was measured after leucovorin administration. Twenty-four mice were treated with leucovorin at doses of 0, 45, 90, or 180 mg/kg/injection x 8 injections spaced over 48 h. Tumor and bone marrow cytosols were assayed for CH2THF by forming ternary complexes with thymidylate synthase and [3H]FdUMP. Tumor CH2THF pools were expanded significantly at the two higher doses. Marrow levels were not different from controls. Groups of tumor bearing mice were treated with saline, leucovorin, 5-fluorouracil or 5-fluourouracil plus leucovorin on an optimal dosage schedule. Measured plus leucovorin on an optimal dosage schedule. Measured from the last day of treatment, these tumors grew to 10 mm root-mean-square diameters in 3.5 +/- 1.4, 5.0 +/- 1.2, 6.5 +/- 1.5, and 9.3 +/- 1.2 days, respectively. Growth rates were significantly different from controls only in the latter two groups.