Background: Studies of the Danish Breast Cancer Group (DBCG)82bc cohort of high-risk breast cancer (BC) patients randomized to +/- postmastectomy radiotherapy (RT) showed that high levels of tumor-infiltrating lymphocytes (TILs) in treatment-naïve tumor predicts improved overall survival (OS), especially for patients with estrogen receptor-negative tumors (ER-) (doi: 10.1080/0284186X.2021.1989629). The association was mediated through distant tumor control rather than local control. We aimed to validate these findings in modernly treated, irradiated BC patients and to investigate the predictive value of TILs in terms of benefit from RT. Methods and Materials: Patients originated from the DBCG-IMN2 cohort (N=980), including node-positive (N+) BC patients with T1-T3 disease, treated between 2007-2014 with breast-conserving surgery or mastectomy, axillary dissection, and loco-regional RT. Irradiation of the internal mammary nodes (IMN-RT) was administered in 460 right-sided patients (47%), and 520 left-sided patients (53%) did not receive IMN-RT (IMN-RT allocated per laterality). All patients had systemic adjuvant therapy including taxanes, trastuzumab and letrozole. Formalin-fixed, paraffin-embedded treatment-naïve tumor tissue was collected from 980 patients. Stromal TILs were estimated on whole slide Hematoxylin & eosin-stained sections following international guidelines. Tumors were categorized into "low" and "high" TILs groups using a 30% cutoff. Endpoints included loco-regional recurrence (LRR), distant metastasis (DM), and OS. Kaplan-Meier and Aalen-Johansen estimators along with univariate Cox regression analysis were used for statistical evaluation. Results: Of the 980 patients, 798 (81%) had estrogen receptor-positive (ER+) tumors, whereas 182 (19%) had ER- tumors. TILs were successfully scored in 911 tumors, and among these, 737 (81%) had low TILs and 174 (19%) high TILs. Patients with ER-/low TILs tumors (N=88) had significantly worse OS compared to ER-/high TILs (N=76) with an adjusted Hazard Ratio (adj. HR) of 0.3 (95% CI: 0.2-0.6), and absolute reduction in OS at 10-years of 30% (47% vs. 77%). No significant difference in OS was observed among patients with ER+ tumors (adj. HR 0.9 (0.6-1.5)), and the interaction test between ER status and TILs was significant (p=0.006). A similar association was found for DM (adj. HR 0.3 (0.2-0.6)), where patients with ER-/low TILs tumors had a 24% absolute higher 10-year risk (42% vs. 18%) compared to ER-/high TILs. No significant difference in DM was observed among ER+ tumors (adj. HR 0.6 (0.4-1.1)). TILs did not impact LRR in patients with either ER- tumors (adj. HR 1.3 (0.3-5.5)) or ER+ tumors (adj. HR 3.2 (0.9-11.0)). The association between RT, TILs and OS as previously described in the DBCG82bc study was further validated since a predictive value of TILs in terms of IMN-RT was seen. Patients with low TILs and right-sided tumors, receiving IMN-RT, had an absolute improvement in OS at 10-years of 9% (79% vs. 70%) compared to patients who did not receive IMN-RT (adj. HR 0.7 (0.5-0.9)). For patients with high TILs, an absolute OS improvement at 10-years of 3% was non-significant (79% vs. 76%). Subdividing by ER status did not affect these results. Conclusions: This study validates previous findings in the DBCG82bc cohort, indicating a robust association between TILs and ER status in irradiated, N+ BC patients. It further supports that poorer OS in irradiated patients with low TILs is mediated through compromised distant tumor control rather than through local failure. The data suggests a predictive value of TILs in terms of IMN-RT, where the addition of IMN-RT was associated with improved OS in patients with low TILs. The results emphasize the potential of TILs as a biomarker in tailoring more personalized RT strategies for BC patients. Citation Format: Demet Özcan, Anders W.M. Nielsen, Jan Alsner, Else Maae, Mette H. Nielsen, Lars Stenbygaard, Lise B.J. Thorsen, Jens Overgaard, Birgitte V. Offersen, Trine Tramm. Validation of the association between TILs, ER status and benefit of radiotherapy in node positive, breast cancer patients: a DBCG study [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr RF2-05.

BACKGROUND AND PURPOSE:Partial breast irradiation (PBI)has beenthe Danish Breast Cancer Group(DBCG) standard for selected breast cancer patients since 2016 based onearlyresults from the DBCG PBI trial.During trial accrual, respiratory-gated radiotherapy was introduced in Denmark. This study aims to investigate the effect of respiratory-gating on mean heart dose (MHD). PATIENTS AND METHODS:From 2009 to 2016 the DBCG PBI trial included 230 patientswith left-sided breast cancer receiving external beam PBI, 40 Gy/15 fractions/3 weeks.Localization of the tumor bed on the planning CT scan, the use of respiratory-gating, coverage of the clinical target volume (CTV), and doses to organs at risk were collected. RESULTS:Respiratory-gating was used in 123 patients (53 %). In 176 patients (77 %) the tumor bed was in the upper and in 54 patients (23 %) in the lower breast quadrants. The median MHD was 0.37 Gy (interquartile range 0.26-0.57 Gy), 0.33 Gy (0.23-0.49 Gy) for respiratory-gating, and 0.49 Gy (0.31-0.70 Gy) for free breathing, p < 0.0001. MHD was < 1 Gy in 206 patients (90 %) and < 2 Gy in 221 patients (96 %). Respiratory-gating led to significantly lower MHD for upper-located, but not for lower-located tumor beds, however, all MHD were low irrespective of respiratory-gating. Respiratory-gating did not improve CTV coverage or lower lung doses. CONCLUSIONS:PBI ensured a low MHD for most patients. Adding respiratory-gating further reduced MHD for upper-located but not for lower-located tumor beds but did not influence target coverage or lung doses. Respiratory-gating is no longer DBCG standard for left-sided PBI.

PURPOSE:To investigate the association between irradiated breast volume and grade 2-3 breast induration three years after radiotherapy in the phase III Danish Breast Cancer Group HYPO trial randomizing patients ≥ 41 years to whole breast irradiation (WBI) with 40 Gy/15fr versus 50 Gy/25fr. METHODS:Treatment plans were available for all Danish patients. Associations between frequency of induration and irradiated volume, age, smoking status, and boost were assessed by logistic regression. A sequential boost was given to patients < 50 years or in case of a narrow (<2 mm) resection margin. RESULTS:RT plans from 1,333 patients were analyzed with 178 (13 %) having grade 2-3 induration. 1135 patients had only WBI. For this group, induration was correlated with irradiated breast volume for patients ≥ 65 years (n = 343, 10 %/22 % for small/large irradiated volumes, p = 0.005) but not for patients aged 50-64 years (n = 792, 11 % for both small and large volumes, p = 0.82). Smoking doubled the frequency irrespective of irradiated volume and age. All patients < 50 years (n = 156) had a boost. A volume effect was found for this group (5 %/21 % induration for small/large volume, p = 0.002). 42 patients ≥ 50 years had a boost and 14 (33 %) had grade 2-3 induration, however, with a p-value > 0.05 due to the few numbers of patients. CONCLUSION:A relationship between irradiated breast volume and 3-year frequency of breast induration was found for patients ≥ 65 years, whilst not for patients aged 50-64 years. Smoking doubled the risk of induration irrespective of volume and age. A dose-induration relationship was seen for boost patients < 50 years.

PURPOSE On the basis of low risk of local recurrence in elderly patients with breast cancer after conservative surgery followed by whole breast irradiation (WBI), the Danish Breast Cancer Group initiated the noninferiority external-beam partial breast irradiation (PBI) trial (ClinicalTrials.gov identifier: NCT00892814 ). We hypothesized that PBI was noninferior to WBI regarding breast induration. METHODS Patients operated with breast conservation for relatively low-risk breast cancer were randomly assigned to WBI versus PBI, and all had 40 Gy/15 fractions. The primary end point was 3-year grade 2-3 breast induration. RESULTS In total, 865 evaluable patients (434 WBI and 431 PBI) were enrolled between 2009 and 2016. Median follow-up was 5.0 years (morbidity) and 7.6 years (locoregional recurrence). The 3-year rate of induration was 9.7% for WBI and 5.1% for PBI ( P = .014). Large breast size was significantly associated with induration with a 3-year incidence of 13% (WBI) and 6% (PBI) for large-breasted patients versus 6% (WBI) and 5% (PBI) for small-breasted patients. PBI showed no increased risk of dyspigmentation, telangiectasia, edema, or pain, and patient satisfaction was high. Letrozole and smoking did not increase the risk of radiation-associated morbidity. Sixteen patients had a locoregional recurrence (six WBI and 10 PBI; P = .28), 20 patients had a contralateral breast cancer, and eight patients had distant failure (five WBI and three PBI). A nonbreast second cancer was detected in 73 patients (8.4%), and there was no difference between groups. CONCLUSION External-beam PBI for patients with low-risk breast cancer was noninferior to WBI in terms of breast induration. Large breast size was a risk factor for radiation-associated induration. Few recurrences were detected and unrelated to PBI.

PURPOSE:The Danish Breast Cancer Group Internal Mammary Node study demonstrated improved 8-year overall survival (OS) with internal mammary node irradiation (IMNI) in patients with node-positive early breast cancer. Here, we present long-term results from the Danish Breast Cancer Group Internal Mammary Node study cohort.PATIENTS AND METHODS:This nationwide, prospective cohort study allocated patients with node-positive early breast cancer to adjuvant radiotherapy with or without IMNI depending on cancer laterality. Patients with right-sided cancer received IMNI. Patients with left-sided cancer were treated without IMNI because of risk of radiation-induced heart disease. Other treatment was independent of laterality. The primary study end point was OS. Secondary end points were distant recurrence and breast cancer mortality. Analyses were by intention to treat.RESULTS:During 2003-2007, 3,089 women were allocated to IMNI (right-sided, n = 1,491) or no IMNI (left-sided, n = 1,598). With a median follow-up of 14.8 years, 589 patients with and 701 patients without IMNI had died. The corresponding 15-year OS rates were 60.1% and 55.4%. The adjusted hazard ratio (HR) for death was 0.86 (95% CI, 0.77 to 0.96; P = .007) in favor of IMNI. The 15-year risk of developing distant recurrence was 35.6% (523 recurrences) and 38.6% (602 recurrences) with vs. without IMNI (adjusted HR, 0.88 [95% CI, 0.79 to 0.99; P = .04]). The 15-year breast cancer mortality with IMNI was 31.7% (467 deaths) compared with 33.9% (537 deaths) without IMNI (adjusted HR, 0.88 [95% CI, 0.78 to 1.00; P = .05]). The distribution of other deaths was similar across groups.CONCLUSION:In patients with node-positive early breast cancer treated with IMNI or without IMNI depending on breast cancer laterality, IMNI reduced the risk of distant recurrence and death from breast cancer, thereby improving long-term survival.

PURPOSE:Given the poor results using hypofractionated radiotherapy for early breast cancer, a dose of 50 Gy in 25 fractions (fr) has been the standard regimen used by the Danish Breast Cancer Group (DBCG) since 1982. Results from more recent trials have stimulated a renewed interest in hypofractionation, and the noninferiority DBCG HYPO trial (ClincalTrials.gov identifier: NCT00909818) was designed to determine whether a dose of 40 Gy in 15 fr does not increase the occurrence of breast induration at 3 years compared with a dose of 50 Gy in 25 fr. PATIENTS AND METHODS:One thousand eight hundred eighty-two patients > 40 years of age who underwent breast-conserving surgery for node-negative breast cancer or ductal carcinoma in situ (DCIS) were randomly assigned to radiotherapy at a dose of either 50 Gy in 25 fr or 40 Gy in 15 fr. The primary end point was 3-year grade 2-3 breast induration assuming noninferiority regarding locoregional recurrence. RESULTS:A total of 1,854 consenting patients (50 Gy, n = 937; 40 Gy, n = 917) were enrolled from 2009-2014 from eight centers. There were 1,608 patients with adenocarcinoma and 246 patients with DCIS. The 3-year rates of induration were 11.8% (95% CI, 9.7% to 14.1%) in the 50-Gy group and 9.0% (95% CI, 7.2% to 11.1%) in the 40-Gy group (risk difference, -2.7%; 95% CI, -5.6% to 0.2%; P = .07). Systemic therapies and radiotherapy boost did not increase the risk of induration. Telangiectasia, dyspigmentation, scar appearance, edema, and pain were detected at low rates, and cosmetic outcome and patient satisfaction with breast appearance were high with either no difference or better outcome in the 40-Gy cohort compared with the 50-Gy cohort. The 9-year risk of locoregional recurrence was 3.3% (95% CI, 2.0% to 5.0%) in the 50-Gy group and 3.0% (95% CI, 1.9% to 4.5%) in the 40-Gy group (risk difference, -0.3%; 95% CI, -2.3% to 1.7%). The 9-year overall survival was 93.4% (95% CI, 91.1% to 95.1%) in the 50-Gy group and 93.4% (95% CI, 91.0% to 95.2%) in the 40-Gy group. The occurrence of radiation-associated cardiac and lung disease was rare and not influenced by the fractionation regimen. CONCLUSION:Moderately hypofractionated breast irradiation of node-negative breast cancer or DCIS did not result in more breast induration compared with standard fractionated therapy. Other normal tissue effects were minimal, with similar or less frequent rates in the 40-Gy group. The 9-year locoregional recurrence risk was low.

Background: Retrospective studies have suggested that chemotherapy-induced leukopenia is associated with improved recurrence-free or overall survival. The SBG 2000-1 trial was designed to verify the favorable prognosis associated with chemotherapy-induced leukopenia in early breast cancer. Patients not experiencing chemotherapy-induced leukopenia were randomized into standard dosed or individually escalated chemotherapy doses based on the grade of leukopenia after a first standard dose. Patients and methods: 1452 women in Sweden and Denmark with operable node-positive or high-risk node-negative breast cancer aged 18-60 years were recruited to participate in this trial. Participants received a first FEC cycle at standard doses (600/60/600 mg/m(2)). Patients (n = 1052) with nadir leukopenia grade 0-2 after the first cycle were randomized between either 6 standard FEC or 6 tailored FEC courses with doses of epirubicin and cyclophosphamide escalated during courses 2 and 3 and thereafter aimed at achieving grade 3 leukopenia. Patients with nadir leukopenia grade 3-4 after the first course continued treatment with standard FEC. Results of the randomized comparison has been published previously. The present study focuses on chemotherapy-induced leukopenia as a covariable with outcome in randomized and non-randomized patients. The prognostic value of leukopenia after course 3, was studied in a Cox model adjusted for cumulative doses of epirubicin and cyclophosphamide. The association of chemotherapy-induced leukopenia with prognosis was a preplanned secondary endpoint for this trial. Results: The eight-year distant disease-free survival was 73%, 77%, 78% and 83% for patients with leucocyte nadir grade 0, 1, 2 and 3-4, respectively. Higher degree of leukopenia was highly significantly associated to improved distant disease-free survival (HR 0.84, 95% CI 0.74-0.96, p = .008) and overall survival (HR 0.87 (0.76-0.99, p = .032). Conclusion: This prospective study confirms that chemotherapy-induced leukopenia is a covariable with outcome in primary breast cancer, even after adjustment for chemotherapy doses.

Chemotherapy for metastatic breast cancer (MBC) is in general given in cycles of maximum tolerated doses to potentially maximize the therapeutic outcome. However, when compared with targeted therapies for MBC, conventional and dose intensified chemotherapy has caused only modest survival benefits during the recent decades, often compromising the quality of life considerably. Navelbine is an antineoplastic agent that has shown efficacy in the treatment of a variety of cancer types, including breast cancer. Early clinical trials involving both breast cancer and lung cancer patients suggest that metronomic dosing of Navelbine might be at least as effective as classical administration (once weekly etc.). The NAME trial compares these two strategies of Navelbine administration in MBC patients.

Background: Navebine is an antineplastic agent that has shown afficacy in the treatment of a variety of solid tumors, including breast cancer. The drug can be given intriavenously, but also as oral tablet treatment. Preclinical studies, as well as clinical observations, suggest that the administration of small, frequent doses of chemotherapy (metronomic dosing) has an effect, not only on cancer cells, but also on endothelialcells in the tumor vasculature. By giving smaller, but more frekvent doses of the drug, higher dose intensity, without corresponding side effects, is optained. Whether treatment under the metronomic principle is superior to conventional treatment, has not yet been validated in the clinic, so this study is hoped to clarify this. Trial design: This is a investigator-initated, prospective randomized fase II, non-blinded multinational, multicentre study running in Denmark and Norway. 200 women diagnosed with HER2 neg metastatic breast cancer will be enroled. Patients are randomized to either: Arm A Clasical treatment: Navelbine Oral: Navelbine Oralâ: 60 mg/m² day 1, day 8 (and day 15), every three weeks for the first cycle. Hereafter 80 mg/m² day 1 and day 8, every three weeks for de following cycles. Or Arm B Metronomic treatment: Navelbine Oralâ: with 3 week cycles of daily doses of 30 mg. (Patients with body surface ≤ 1,54 m² or 65 Years or more start on 20 mg daily.) Treatment is given first or second line (chemotherapy). The primary Objectives is to evaluate the Disease Control Rate (CR + PR + SD, SD > 3 months) in the two arms. Secondary Objectives are to compare the duration of Disease Control, TTP, RR, DR and OS and side effects for the two regimens. Also Evaluation of the Global Health Status/QoL, on the basis of the EORTC QOL C30 questionnaire is made. Finally a translational study to explore the potential of biomarkers during metronomic therapy is performed.The patients will be treated until progression or to high toxicity, or until the patient wishes discontinuation. Clinical trial identification: EudraCT: 2016-002165-63. Health Board no: 2017040059. Approved by Research Ethics Commitee and Data Protection Agency June 2017. Legal entity responsible for the study: Sven Tyge Langkjer. Funding: The study is an investigator-initiated study, but financially supported by the pharmaceutical company Pierre Fabre. Disclosure: All authors have declared no conflicts of interest.