ctDNA quantification improves estimation of outcomes in patients with high-grade osteosarcoma: a translational study from the OS2006 trial

BACKGROUND

Osteosarcoma stratification relies on clinical parameters and histological response. We developed a new personalized stratification using less invasive circulating tumor DNA (ctDNA) quantification.

PATIENTS AND METHODS

Plasma from patients homogeneously treated in the prospective protocol OS2006, at diagnosis, before surgery and end of treatment, were sequenced using low-passage whole-genome sequencing (lpWGS) for copy number alteration detection. We developed a prediction tool including ctDNA quantification and known clinical parameters to estimate patients' individual risk of event.

RESULTS

ctDNA quantification at diagnosis (diagCPA) was evaluated for 183 patients of the protocol OS2006. diagCPA as a continuous variable was a major prognostic factor, independent of other clinical parameters, including metastatic status [diagCPA hazard ratio (HR) = 3.5, P = 0.002 and 3.51, P = 0.012, for progression-free survival (PFS) and overall survival (OS)]. At the time of surgery and until the end of treatment, diagCPA was also a major prognostic factor independent of histological response (diagCPA HR = 9.2, P < 0.001 and 11.6, P < 0.001, for PFS and OS). Therefore, the addition of diagCPA to metastatic status at diagnosis or poor histological response after surgery improved the prognostic stratification of patients with osteosarcoma. We developed the prediction tool PRONOS to generate individual risk estimations, showing great performance ctDNA quantification at the time of surgery and the end of treatment still required improvement to overcome the low sensitivity of lpWGS and to enable the follow-up of disease progression.

CONCLUSIONS

The addition of ctDNA quantification to known risk factors improves the estimation of prognosis calculated by our prediction tool PRONOS. To confirm its value, an external validation in the Sarcoma 13 trial is underway.

Abstract P5-16-04: Evaluation of autologous fat grafting local morbidity (fat necrosis and biopsy rates) in breast reconstruction after breast cancer: A retrospective study on 257 patients in Oscar Lambret Center

Background.Autologous fat grafting (AFG) is a widely used procedure in breast reconstruction after breast cancer. Indications are in constant increase but there is a lack of dataabout global morbidity, especially fat necrosis and management of local complications. The purpose of this study was to evaluate the complications rate in term of abnormal clinical examination or imaging and the proportion of additional explorations.

Methods. We retrospectively reviewed the computerized files of consecutive patients who underwent AFG for breast reconstruction after breast cancer or for preventive surgery and aesthetic sequelae after lumpectomy in the Oscar Lambret center between January 2013 and December 2016. Fat grafts were harvested with a fat trap then processed and injected according the Coleman technique. We collected demographics, operative details, local complications, incidence of palpable masses and/or suspicious breast imaging findings leading to additional explorations (breast imaging or biopsy), and locoregional cancer recurrence. Descriptive statistics were generated.

Results. Over a 4-year period, 257 women underwent autologous fat grafting for breast reconstruction and aesthetic sequelae after lumpectomy. Their mean age was 50 years [range 28-75], the mean BMI was 25 [range 18-44], 26% (n=66) were smoking and 74% (n=190) underwent radiotherapy. A total of 303 breasts were operated by 270 mastectomies (89%) or33 lumpectomies (11%). The reconstruction was delayed in 63% (n=171) and the main techniques used were breast implant (44%, n=119) and autologous latissimus dorsi (31%, n=84). The mean number of fat grafting procedures was 1,9 per patient [range 1-7] with a mean volume of 181 mL [range 30-535]. The mean time interval between cancer diagnosis and first fat graft session was 56 months [range 3-285], and the follow-up ranged from 0 to 51 months (mean=16). The prevalence of donor site complications was 6% (n=16) and infections was 2% (n=5). Sixty six (25,6%) patients had a clinically palpable lesion and 54 (21%) underwent additional imagings, mostly by ultrasounds (53 patients, 98%) except the usual follow-up. Twenty one biopsies (8%) were performed and showed 16 benign results (76,2%) and 5 malignant results (23,8%) leading to 6,2% of fat necrosis and 1,9% of locoregional recurrence after AFG in our study.Tobacco (p=0.45), BMI (p=0.95), radiotherapy (p=0.56) and amount of fat grafted ( p=0.09) didn't appear to be risk factors for fat necrosis.

Conclusions. A good knowledge of local complications by surgeons and radiologists enables to avoid systematic and repeated further imaging explorations. Multicentric, prospective studies with long term follow up and evaluation of patients reported outcomes are needed to evaluate anxiety generated by biopsies and costs generated by repeated imagings.

Key words: autologous fat grafting, breast cancer, local morbidity, fat necrosis.

Citation Format: Hannebicque K, Renaudeau C, Giard S, Regis C, Boulanger L, Bogart E, Le Deley M-C, Ceugnart L, Chauvet M-P. Evaluation of autologous fat grafting local morbidity (fat necrosis and biopsy rates) in breast reconstruction after breast cancer: A retrospective study on 257 patients in Oscar Lambret Center [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-16-04.

Prediction of fluid responsiveness by a continuous non-invasive assessment of arterial pressure in critically ill patients: comparison with four other dynamic indices

BACKGROUND

We evaluated the ability of an infrared photoplethysmography arterial waveform (continuous non-invasive arterial pressure, CNAP) to estimate arterial pulse pressure variation (PPV). We compared the ability of non-invasive PPV to predict fluid responsiveness with invasive PPV, respiratory variation of pulse contour-derived stroke volume, and changes in cardiac index induced by passive leg raising (PLR) and end-expiratory occlusion (EEO) tests.

METHODS

We measured the responses of cardiac index (PiCCO) to 500 ml of saline in 47 critically ill patients with haemodynamic failure. Before fluid administration, we recorded non-invasive and invasive PPVs, stroke volume variation, and changes in cardiac index induced by PLR and by 15 s EEO. Logistic regressions were performed to investigate the advantage of combining invasive PPV, stroke volume variation, PLR, and EEO when predicting fluid responsiveness.

RESULTS

In eight patients, CNAP could not record arterial pressure. In the 39 remaining patients, fluid increased cardiac index by ≥15% in 17 'responders'. Considering the 195 pairs of measurements, the bias (sd) between invasive and non-invasive PPVs was -0.6 (2.3)%. The areas under the receiver operating characteristic (ROC) curves for predicting fluid responsiveness were 0.89 (95% confidence interval, 0.78-1.01) for non-invasive PPV compared with 0.89 (0.77-1.01), 0.84 (0.70-0.96), 0.95 (0.88-1.03), and 0.97 (0.91-1.03) for invasive pulse pressure, stroke volume variations, PLR, and EEO tests (no significant difference). Combining multiple tests did not significantly improve the area under the ROC curves.

CONCLUSIONS

Non-invasive assessment of PPV seems valuable in predicting fluid responsiveness.