Abstract OT2-15-01: COntinue the SaMe systemic therapy after local ablative therapy for Oligoprogression in metastatic breast cancer - the COSMO study

Background

Patients with metastatic breast cancer (MBC) are usually treated with palliative systemic therapy until progression or unacceptable toxicity. When progression occurs, clinicians typically switch to the next line of systemic therapy. However, this strategy might be suboptimal in case of mixed response or oligoprogression. Oligoprogression refers to a situation in which inter-lesion heterogeneity causes one or few metastatic lesions to progress while the vast majority of the metastatic burden responds to the treatment. Locally ablative treatment of the progressive lesion(s) with radiotherapy, resection or radiofrequency ablation may enable continuation of otherwise effective systemic treatment. Solid data to support this approach, however, is lacking at this moment.

Study design

The COSMO study is an investigator-initiated single-arm phase 2 study. It is intended to be a multicenter study.

Eligibility criteria

Patients with MBC and oligoprogression, defined as 1-2 progressive lesions while the majority of the metastatic burden remains stable or in remission, are eligible. Current systemic therapy must be 1st or 2nd line and patients must have responded to this systemic therapy for at least six months prior to the occurence of oligoprogression. The aberrant lesion must be amenable to locally ablative therapy. All eligibility criteria may be found in table 1: eligibility criteria. Aim To investigate efficacy of local ablation of aberrant lesions combined with continuation of the same systemic therapy in patients with oligoprogression of MBC.

Primary endpoint:

Progression-free survival rate at six months (PFS-6).

Secondary endpoints:

- PFS

- Overall survival

- Time to next line of systemic therapy

Primary and secondary endpoints will also be stratified by localization of progressive lesion and BC subtype (ER+/HER2- vs. HER2+ vs. TN).

- Local control rate of lesion treated with LAT at 12 months

- Complications due to LAT

- Quality of life

- Incidence of visceral crisis

Exploratory endpoints:

- Biomarkers, including receptor (ER/PR/HER2), PD-L1 and gene expression patterns in biopsies from progressive and responding lesions

- Prognostic value of ctDNA at oligoprogression and during the course of treatment

Statistical methods

An A’hern design was chosen to conduct this study. As null-hypothesis (H0), PFS-6 rate ≤ 25% is set. The alternative hypothesis (H1) is PFS-6-rate ≥ 40%. Hypotheses were set to meet criteria for clinical significance, as stated by experts in the field. Setting one-sided α = 0.05 and a desirable power=95%, 107 evaluable patients are needed. To account for 10% of the patients to be unevaluable, 118 included patients are needed. An early stopping rule for safety is applicable: if out of the first 45 patients ≥4 of these patients have developed visceral crisis, the study will be closed early.

Accrual

Start: July 2022

Target: 118 patients

Estimated accrual time: 2-3 years

Further information

Corresponding author: c.almekinders@nki.nl

Clinicaltrials.gov identifier: NCT05301881

This study is funded by the Maarten van der Weijden foundation.

This study was developed during the 21st EORTC/ESMO/AACR workshop on methods in clinical cancer research (MCCR).

Table 1. Eligibility criteria.

Citation Format: Cornelia AM Almekinders, Tessa G Steenbruggen, Ingrid A. Mandjes, Marta Lopez-Yurda, Monique EMM Bos, Terry G Wiersma, Gabe S. Sonke. COntinue the SaMe systemic therapy after local ablative therapy for Oligoprogression in metastatic breast cancer - the COSMO study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-15-01.

Survival and prognostic factors in oligometastatic breast cancer

BACKGROUND

Guidelines for oligometastatic breast cancer (OMBC) propagate multimodality treatment including polychemotherapy and local ablative treatment (LAT) of all lesions. The aim of this approach is prolonged disease remission, or even cure. Long-term outcomes in OMBC and factors associated with prognosis are largely unknown, due to the rarity of this condition. We report overall survival (OS), event-free survival (EFS), and prognostic factors in a large real-world cohort of patients with OMBC.

METHODS

Patients with breast cancer and 1-3 distant metastatic lesions, treated in the Netherlands Cancer Institute between 1997 and 2020, were identified via text mining of medical files. We collected patient, tumor and treatment characteristics. The Kaplan-Meier method was used to calculate OS and EFS estimates, and Cox regression analyses to assess prognostic factors.

RESULTS

The cohort included 239 patients, of whom 54% had ERpos/HER2neg, 20% HER2pos and 20% triple negative disease. Median follow-up was 88.0 months (95% confidence interval (CI) 82.9-93.1) during which 107 patients died and 139 developed disease progression/recurrence; median OS was 93.0 months (95%CI 66.2-119.8). Factors associated with OS in multivariable analysis were subtype, disease-free interval and radiologic response to first-line systemic therapy; LAT was associated with EFS, but not OS.

CONCLUSIONS

In this large real-world cohort of patients with OMBC, OS and EFS compare favorably to survival in the general MBC population. Radiologic complete response to first-line systemic therapy was associated with favorable OS and EFS, indicating the importance of early optimal systemic therapy. The value of LAT in OMBC requires further study.

Survival and prognostic factors in oligometastatic breast cancer

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Background: Clinical guidelines for the treatment of oligometastatic breast cancer (OMBC) propagate multimodality treatment including polychemotherapy and ablative local therapy for all detected disease. The aim of this aggressive approach is prolonged disease remission, or even cure, but randomized data to support this strategy lack and long-term outcomes are not well known. We report prognostic factors, and event-free survival (EFS) and overall survival (OS) in a real world, single center cohort of patients with OMBC with long-term follow-up. Methods: Patients with breast cancer and 1-3 distant metastatic lesions who underwent treatment in the Netherlands Cancer Institute were identified via text mining of medical files. We collected patient, tumor and treatment characteristics as well as recurrence and survival data from the medical records. The Kaplan-Meier method was used to calculate EFS and OS estimates, and Cox regression analyses to assess potential prognostic factors. Results: The cohort included 239 patients (of whom two males), diagnosed between 1997 and 2020. Median follow-up was 75.0 months. Fifty-one percent had hormone receptor (HR)-positive/ human epidermal growth factor receptor 2 (HER2)-negative disease, 20.1% had HER2-positive disease, and 19.2% had triple negative (TN) disease. Median age at OMBC diagnosis was 49.0 years and 47.3% of patients had synchronous disease (metastases ≤6 months of primary diagnosis). Most patients (81.2%) received chemotherapy and local therapy (surgery, radiotherapy and/or radiofrequency ablation) of all metastatic lesions (83.7%). Of 239 patients, 134 experienced disease recurrence with a median EFS of 40.0 months (95% confidence interval (CI): 28.6-51.4); 97/239 died and median OS was 93.0 months (95% CI 74.5-111.5). The table shows factors associated with favorable OS in multivariable analysis. Cox regression analysis for EFS showed similar results. Conclusions: In this large real world cohort of OMBC patients, EFS and OS compare favorably to survival in the general MBC population. HR-positive and/or HER2-positive subtypes, synchronous disease or long DFI, favorable response to first-line systemic therapy and local therapy of all distant lesions are independently associated with better survival. Future studies should be directed at optimizing patient selection and therapy choices in this population with the potential for cure. [Table: see text]

Toward omitting sentinel lymph node biopsy after neoadjuvant chemotherapy in patients with clinically node-negative breast cancer

BACKGROUND

The nodal positivity rate after neoadjuvant chemotherapy (ypN+) in patients with clinically node-negative (cN0) breast cancer is low, especially in those with a pathological complete response of the breast. The aim of this study was to identify characteristics known before surgery that are associated with achieving ypN0 in patients with cN0 disease. These characteristics could be used to select patients in whom sentinel lymph node biopsy may be omitted after neoadjuvant chemotherapy.

METHODS

This cohort study included patients with cT1-3 cN0 breast cancer treated with neoadjuvant chemotherapy followed by breast surgery and sentinel node biopsy between 2013 and 2018. cN0 was defined by the absence of suspicious nodes on ultrasound imaging and PET/CT, or absence of tumour cells at fine-needle aspiration. Univariable and multivariable logistic regression analyses were performed to determine predictors of ypN0.

RESULTS

Overall, 259 of 303 patients (85.5 per cent) achieved ypN0, with high rates among those with a radiological complete response (rCR) on breast MRI (95·5 per cent). Some 82 per cent of patients with hormone receptor-positive disease, 98 per cent of those with triple-negative breast cancer (TNBC) and all patients with human epidermal growth factor receptor 2 (HER2)-positive disease who had a rCR achieved ypN0. Multivariable regression analysis showed that HER2-positive (odds ratio (OR) 5·77, 95 per cent c.i. 1·91 to 23·13) and TNBC subtype (OR 11·65, 2·86 to 106·89) were associated with ypN0 status. In addition, there was a trend toward ypN0 in patients with a breast rCR (OR 2·39, 0·95 to 6·77).

CONCLUSION

The probability of nodal positivity after neoadjuvant chemotherapy was less than 3 per cent in patients with TNBC or HER2-positive disease who achieved a breast rCR on MRI. These patients could be included in trials investigating the omission of sentinel node biopsy after neoadjuvant chemotherapy.

Geometrical and dosimetric evaluation of breast target volume auto-contouring

Background and purpose

Automatic delineations are often used as a starting point in the radiotherapy contouring workflow, after which they are manually reviewed and adapted. The purpose of this work was to quantify the geometric differences between automatic and manually edited breast clinical target volume (CTV) contours and evaluate the dosimetric impact of such differences.

Materials and methods

Eighty-seven automatically generated and manually edited contours of the left breast were retrieved from our clinical database. The automatic contours were obtained with a commercial auto-segmentation toolbox. The geometrical comparison was performed both locally and globally using the Dice score and the 95% Hausdorff distance (HD). Two treatment plans were generated for each patient and the obtained dosimetric differences were quantified using dose-volume histogram (DVH) parameters in the lungs, heart and planning target volume (PTV). An inter-observer variability study with four observers was performed on a subset of ten patients.

Results

A median Dice score of 0.95 and a median 95% HD of 9.7 mm were obtained. Larger breasts were consistently under-contoured. Cranial under-contouring resulted in more than 5% relative decrease in PTV coverage in 15% of the patients while lateroposterior over-contouring increased the lung V_20Gy by a maximum of 2%. The inter-observer variability of the PTV coverage was smaller than the difference between PTV coverage achieved by the automatic and the consensus contours.

Conclusions

Cranial under-contouring resulted in under-treatment, while lateroposterior over-contouring resulted in an increased lung dosage that is clinically irrelevant, showing the need to consider dose distributions to assess the clinical impact of local geometrical differences.

A robust volumetric arc therapy planning approach for breast cancer involving the axillary nodes

We quantify the robustness of a proposed volumetric-modulated arc therapy (VMAT) planning and treatment technique for radiotherapy of breast cancer involving the axillary nodes. The proposed VMAT technique is expected to be more robust to breast shape changes and setup errors, yet maintain the improved conformity of VMAT compared to our current standard technique that uses tangential intensity-modulated radiation therapy (IMRT) fields. Treatment plans were created for 10 patients. To account for anatomical variation, planning was carried out on a computed tomography (CT) with an expanded breast, followed by segment weight optimization (SWO) on the original planning CT (VMAT + SWO). For comparison purposes, tangential field IMRT plans and conventional VMAT (cVMAT) plans were also created. Anatomical changes (expansion and contraction of the breast) and setup errors were simulated to quantify changes in target coverage, target maximum, and organ-at-risk (OAR) doses. Finally, robustness was assessed by calculating the actual delivered dose for each fraction using cone-beam CT images acquired during treatment. Target coverage of VMAT + SWO was shown to be significantly more robust compared to cVMAT technique, against anatomical variations and setup errors. Sensitivity of the clinical target volume (CTV) V95% is -5%/cm of expansion for the proposed technique, which is identical to the IMRT technique and much lower than the -22%/cm for cVMAT. Results are similar for setup errors. OAR doses are mostly insensitive to anatomical variations and the OAR sensitivity to setup variations does not depend on the planning technique. The results are confirmed by dose distributions recalculated on cone-beam CT, showing that for VMAT + SWO the CTV V95% remains within 2.5% of the planned value, whereas it deviates by up to 7% for cVMAT. A practical VMAT planning technique is developed, which is robust to daily anatomical variations and setup errors.

Concurrent chemoradiotherapy for large-volume locally-advanced non-small cell lung cancer

PURPOSE

Patients with large volume stage III non-small cell lung cancer (NSCLC) are often excluded from concurrent chemoradiotherapy (CRT) protocols due to fears about excessive toxicity and poor survival. Patients with N3 nodal disease may be excluded for the same reason. We have routinely accepted fit patients in both the above groups for CRT if they met our planning parameters. We analyzed toxicity and survival outcomes for patients undergoing CRT with a planning target volume (PTV) exceeding 700 cc, either with or without N3 nodal disease, or a PTV less then 700 cc with N3 disease.

MATERIALS AND METHODS

Single center, retrospective study of patients with stage III NSCLC treated with CRT between 2004 and 2011.

RESULTS

121 patients were eligible, with 81% (98/121) having a PTV>700 cc (of whom 33% (32/98) had N3 nodal disease) and 19% (23/121) having N3 disease and a PTV≤700 cc. Grade ≥3 esophagitis and pneumonitis were recorded in respectively 34% and 4% of all patients. Median follow-up for all patients was 37.6 months (mo). Median overall (OS) and progression-free (PFS) survivals were 15.7 mo and 11.6 mo, respectively, OS for all patients with PTV>700 cc was 14.5 mo (19.5 mo with N3 and 13.2 mo without N3), compared to 26.5 mo for PTV≤700 cc with N3 (p=0.009). About 1 in 4 patients with PTV>700 cc died within 6 mo of starting radiotherapy (this was associated with Charlson comorbidity index [CCI]≥1), while about 18% were alive at 3 years.

CONCLUSION

Patients undergoing CRT for stage III NSCLC with a PTV>700 cc, with or without N3 nodal disease, had a significantly shorter OS than patients with PTV≤700 cc with N3. Patients with PTV>700 cc and with CCI≥1, had a significantly higher risk of early death but longer-term survivors with PTV>700 cc are observed. The PTV and CCI should be considered in clinical decision making and used as stratification factors in future trials.

Contrast vaginography is more accurate than the radiopaque rod for localization of the vagina

PURPOSE

To compare the radiopaque vaginal rod method with contrast vaginography in localization of the vagina.

METHODS AND MATERIALS

In 25 female patients who needed pelvic radiotherapy, both our standard localization procedure using the vaginal rod and a localization procedure using contrast vaginography were performed. As a rod can change the position of the vagina, contrast vaginography was considered to display the true anatomic position of the vagina. The corresponding rod and nonrod X-rays of each patient were compared. The distance from the true vaginal apex to the displaced vaginal apex (= the top of the rod) was measured in the sagittal plane. This distance was called the inaccuracy of the rod method. Furthermore, the size of the vaginal vault was measured using the contrast vaginography.

RESULTS

The median inaccuracy of the rod method was 13 mm (range 2 to 24 mm). The maximal width of the vagina ranged from 24 to 68 mm in the frontal plane (median 39 mm) and from 3 to 22 mm in the sagittal plane (median 10 mm).

CONCLUSION

The rod method is not accurate to localize the vagina. Furthermore, the rod gives no information on the actual size of the vaginal vault. Contrast vaginography is the method of choice to localize the vagina.

Imaging of anorectal disease

BACKGROUND

Over the past two decades developments in imaging have changed the assessment of patients with anorectal disease.

METHODS

The literature on imaging techniques for anorectal diseases was reviewed over the period 1980-1999.

RESULTS

For the staging of primary rectal tumours, phased array magnetic resonance imaging (MRI) may be regarded as the most appropriate single technique. The combination of endosonography or endoluminal MRI with ultrasonography or spiral computed tomography yields similar results. All techniques have limitations both for local staging and in the assessment of distant metastases. MRI or positron emission tomography is preferable for tumour recurrence. For perianal fistula, high-resolution MRI (phased array or endoluminal) is the technique of choice. For constipation, defaecography is the preferred technique, nowadays with emphasis on functional information. The role of magnetic resonance defaecography is currently being evaluated. For faecal incontinence, endosonography and endoluminal MRI give similar results in detecting sphincter defects; endoluminal MRI has the advantage of detecting external sphincter atrophy.

CONCLUSION

High-resolution MRI, endosonography and defaecography are currently the optimal imaging techniques for anorectal disease.

The constipated stomach. An underdiagnosed problem in patients with abdominal pain?

The number of dyspeptic patients with upper abdominal pain that are referred for investigation is increasing and will undoubtedly continue to increase, because these days peptic ulcer disease is increasingly becoming a primary care management issue, the specialist being left to deal with the patients who cannot be helped by antibiotics and antisecretory drugs prescribed by their general practitioner. Many of these patients are referred for an upper endoscopy to rule out organic disease. Carefully taken history, however, shows that a great number of those dyspeptics, on the basis of their clinical manifestations, do have a functional gastrointestinal disorder, representing the 'irritable gut'. A probable better term reflecting the direct relation is the syndrome of 'the constipated stomach'. In our opinion these patients are an important and increasing clinical problem for general practitioners, gastroenterologists, surgeons and physicians. The aim of this article is to make the practitioner aware of advancements in understanding pathophysiologic and psychosocial processes, as well as to give an overview of the great overlap between many functional gastrointestinal disorders, the important role of history-taking and some insights into the functional rectal outlet syndrome.

Dynamic rectal examination: its significant clinical value

The aim of the present study was to carry out a proper correlation between patients' clinical symptoms and the radiological findings obtained by dynamic rectal examination (DRE). At DRE, the small bowel and in females the vagina are routinely opacified in addition to defecography. A prospective study of 248 consecutive patients (193 women and 55 men, ratio 3.5:1) and 14 control subjects was conducted. The parameters assessed included the anorectal angle, the position of the anorectal junction, and the total movement of the pelvic floor during squeezing and defecation. Anatomical changes as rectoceles, enteroceles and intussusceptions were also observed. Based on the findings, the following conclusions can be drawn. There is no indication for measurement of the central or posterior anorectal angle. There is no indication for measurement of the perineal ascent, perineal descent, and anorectal junction level. Anterior rectoceles occur very frequently in females, and are only of clinical relevance if the patients need digital vaginal support to facilitate defecation. DRE is a sensitive method for diagnosing enteroceles and intussusceptions.

Hysterectomy: the anorectal pitfall. A guideline for evaluation

Constipation following routine hysterectomy seems to occur more frequently than originally thought. Treatment depends on whether the patient is referred and to whom. Physical examination seems of limited value. Proper protocols for evaluation of complaints after hysterectomy are mandatory. Colonic transit studies and dynamic rectal examination could be useful. We found an overrepresentation of enteroceles in the hysterectomy group. Management of these abnormalities seems much more complicated than was previously thought. Prospective studies are needed to investigate anorectal disorders after hysterectomy.

Dynamic rectal examination (defecography)

Dynamic rectal examination (DRE), first described in 1952, is becoming more widely used in the dynamic evaluation of pelvic floor and anorectal motility disorders. It is a minimally invasive investigation which is well tolerated by patients and provides information about the anosphincteric, puborectal and levator muscle in addition to insight in rectal function and structure. DRE is the only investigation of anorectal function that can give detailed anatomical information such as the presence of a rectocele, an enterocele and an intussusception. DRE should be performed in a quiet environment with a minimum number of investigators present. Any technique which attempts to study the defecatory mechanism must be a compromise since the patient is aware of being studied. In order to defecate on command the radiologist must make the patient comfortable before starting the investigative procedures to avoid any possible psychological inhibition. We have not encountered any failures in this regard. The relative value of the radiological findings with respect to symptoms and complaints is insufficiently known. This has been the main incentive to design carefully and carry out a large prospective critical evaluation of various aspects of DRE in particular the correlation with objective findings and symptoms. Moreover an assessment has been made of its overall clinical utility (Wiersma, 1994). It is very likely that DRE is both investigator- and technique-dependent. To ensure that the study is as physiological as possible the contrast medium used to fill the rectum needs to be semi-solid and malleable equivalent in consistency to a normal faecal bolus. For proper anatomical studies in females vaginal opacification is mandatory. The acceptance of vaginal contrast was good. Only 4% of the female patients preferred not to have the vaginal application of contrast. The technique of DRE when performed with small bowel and vaginal opacification provides a sensitive and objective method of detecting enteroceles. A substantial number of female patients related the onset of their complaints to hysterectomy. In female patients with constipation there was a significantly higher incidence of enteroceles in patients with a hysterectomy compared to the group of females without hysterectomy. Because of these findings a series of pre- and postoperative DREs in hysterectomy patients are on their way in our institute. Unlike a rectocele which is usually most obvious during defecation, enteroceles are sometimes appreciated only with repeated straining after evacuation.(ABSTRACT TRUNCATED AT 400 WORDS)