Abstract P4-02-06: Clinical and biological predictors of lymph node involvement in patients with early breast cancer for adjuvant treatment personalization

Background: Over the last years, the management of patients with node positive early breast cancer has gone through important innovations. On the medical side, new targeted therapies such as olaparib and abemaciclib have been introduced, with promising results on the invasive disease-free survival. Moreover, sparing axillary lymph node dissection has proven to be noninferior in terms of overall survival. However, no tools are currently available to predict lymph node involvement before definitive surgical evaluation. The aim of the study was to analyze clinical and pathological characteristics of patients with node positive early breast cancer to explore potential risk profiles associated with a ≥3 nodal involvement. Methods: The study retrospectively analyzed 335 node-positive breast cancer patients treated at the Breast Unit of the CRO Aviano National Cancer Institute, between 2017 and 2021. Data regarding primary tumor biological features, lymph node involvement and surgical approach were collected. Associations between clinico-pathological characteristics and ≥3 lymph node involvement were tested through stepwise logistic regression and the gradient boosting machine learning algorithm (GBM). Results: Among the 335 analyzed patients, 87.0% had a primary tumor < 5 cm, with a single positive lymph node in 73.3% of cases. Hormone receptors were mainly positive (respectively 93.5% and 83.4% for estrogen and progesterone receptors). Tumor grade was most frequently well differentiated (Grade 1 in 60.7%), with a Ki67 < 20% (59.5%). After multivariable logistic regression, a tumor size ≥ 3 cm (OR 3.24, CI95% 1.47-7.17, p = 0.004), the presence of massive lymphovascular stromal invasion (OR 2.50, CI95% 1.02-6.14, p = 0.045) and 2 or more positive sentinel lymph nodes at surgical evaluation (OR 6.08, CI95% 3.34-11.05, p < 0.001) were associated with a higher risk of identifying ≥ 3 positive lymph nodes after subsequent axillary dissection. Similar results were observed in the luminal-like cohort. A GBM machine learning model was then developed with a 0.77 Area Under the Curve. Features with the highest relative importance (RI) were single sentinel node involvement (RI 16.1873), followed by tumor size ≥ 3 cm (RI 10.2024), ≥2 positive sentinel lymph nodes (RI 8.5050) and lymphovascular stromal invasion (4.0217). Consistently, number of positive sentinel lymph nodes and tumor size were the predominant features in all top 20 GBM models. Conclusions: The present study explored the definition of risk profiles linked to 3 or more positive lymph nodes based on clinical and pathological features. It, moreover, tested the feasibility of developing machine learning classifiers to support future clinical decision-making. Due to the growing complexity of the adjuvant setting, finding a balance between minimally invasive surgical and staging approaches and risk definition for treatment personalization will become increasingly critical.

Citation Format: Tania Pivetta, Brenno Pastò, Martina Urbani, Elisabetta Benozzi, Nicola De Pascalis, Tiziana Perin, Mario Mileto, Bruno Pasquotti, Erica Piccoli, Lorenzo Vinante, Chiara Bampo, Silvia Bolzonello, Mattia Garutti, Milena Nicoloso, Serena Corsetti, Simona Scalone, Lucia da Ros, Paola di Nardo, Camilla Lisanti, Simon Spazzapan, Barbara Belletti, Michele Bartoletti, Lorenzo Gerratana, Samuele Massarut, Fabio Puglisi. Clinical and biological predictors of lymph node involvement in patients with early breast cancer for adjuvant treatment personalization [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 P4-02-06.

Clinical relevance of Paliperidone Palmitate three-month intramuscular injection formulation: an Italian Real-World, Retrospective, one-year Mirror Image Study

Introduction

Paliperidone Palmitate 3-month (PP3M) formulation, introduced in Italy since 2017, is an effective and safety therapeutic option for patients with schizophrenia, clinically stable with 1-month formulation (PP1M). Only a few “Real World” studies investigated the clinical relevance of PP3M and the long-term clinical and health resource utilization outcomes.

Objectives

The aim of this retrospective, mirror image study was to evaluate the efficacy of PP3M in terms of continuity of care and number of hospitalizations.

Methods

Fifty outpatients treated with Paliperidone Palmitate (PP) were recruited from a Community Mental Health Centre (CMHC) in Milan. Statistical analysis were conducted with SPSS 26. Frequencies of hospitalization 6 months before and after the start of PP3M were compared using the McNemar test, setting the significance to p<0.05.

Results

This study involved 34 patients (68%) treated with PP1M and 16 (32%) treated with PP3M.The median time interval between PP1M and PP3M was 14 months. After the switch to PP3M, 69% of patients continued to visit the CMHC with an unchanged frequency (50% once/month, 6% more than once/month), while 31% with a decreased frequency (once/3 months). No patient increased the frequency of CMHC visits or started visiting it discontinuously. 44% of subjects had had at least one hospitalization prior to the switch and no hospitalizations after (p=0.016). Moreover, no patients showed increased hospitalizations

Conclusions

In this study PP3M clinical relevance was confirmed comparing pre-initiation and post-initiation 6-months time intervals: hospitalizations number significantly decreased, while the continuity of care was preserved. Further studies on a greater sample are necessary to support these preliminary data.

Disclosure

No significant relationships.

Incidence and predictive factors of non adherence to therapy in young adults attending a psycho social center in Milan: a retrospective observational “Real world” study

Introduction

Non adherence to psychotropic drugs is associated with negative outcomes, including hospitalizations, aggressive behaviors, suicide attempts and increased premature mortality. It represents a psychiatric challenge, especially in young adults who show higher risk of non-adherence to treatment

Objectives

Firstly this study evaluates the incidence of non-adherence to therapy in 18-24 years patients from a Psycho-Social Center in Milan; and then to analyze the predictive factors of non-adherence.

Methods

In this retrospective “Real Life” observational study, 120 outpatients aged 18 to 24 years, from Psycho-social Center of L. Sacco University Hospital in Milan, were recruited in 2019. Non-adherence to treatment, according to the World Health Organization, was considered “a modality of assuming medications that does not correspond to healthcare professionals’ recommendations”. Statistical analysis were performed with chi-square, ANOVA and linear regression tests, setting significance to p<0.05.

Results

88 of 120 outpatients (73.3%) received an indication to psychopharmacological treatment. Of these, 23 (26.1%) did not show adherence to therapy. Results showed a positive association between non-adherence and increased hospitalizations (p <.01), oral antipsychotics (p<.05) and drop-out rates (p<.001). A significant correlation was also observed between non-adherence and Intellectual Disability (p<.05), Bipolar Disorder (p<.05), psychotic symptoms (p<.05), alterations in affectivity and mood (p<.005), alterations in sleep pattern (p<.05), school dropout (p<.05) and poor family support (p<.01).

Conclusions

This study confirms that non-adherence has a relevant incidence in young-adults psychiatric population, highlighting the importance of effective and structured assessment in clinical practice to identify predictive factors and risk profiles associated with this phenomenon.

Disclosure

No significant relationships.

P2882Sustainable organization of a management model for CIED remote control: data from a single tertiary center

Introduction

The remote control (RC) of CIED has become necessary, though the human resources and technical facilities needed are limited. In most of Centers, the ratio of RC CIED /CIED with in-office follow up, is continuously increasing and is expected to reach the 100% of CIED remotely controlled.

We sought assess an organizational model based on available facilities and a long-term projection of RC data burden. Pacemakers, ICD and implantable loop recorders were considered.

Methods

The total population served by the Hospital area has been obtained (271.260 citizens), timed at December 31st 2014. By checking our Hospital data files, the total number of followed up CIED patients timed at January 1st 2011 (3995; 1.47% of all population), was compared with the same data timed at January 1st 2015 (3902; 1.43% of all population), in order to the check for the “stability” of that data over time.

At the analyzed time 1582/3902 (40,5%) of CIED were followed by RC.

We have then considered an yearly average of 465 CIEDs implanted/replaced (yearly implants 2012 to 2015) and excluded a roughly 10% of them because not provided of RC facilities (unwilling patients or CIED not RC “ready”); all the other patients were provided with RC. On these basis, we can assume a ratio of RC CIEDs /non-RC CIED, deemed to increase by 10 to 11% per year, to reach the break-even of 100% of RC CIEDs, in 2021 (projection).

The number of RC transmissions (Tx) have been gathered in 5 types of events (Fig. left upper).

The timing of RC patient managing from opening the CIED web site to complete patient file assessment (RC file analysis) performed by expert nurses, was arbitrarily calculated over a sample of 10 Tx per day in 3 different days.

Results

Of 3902 CIED patient, 1582 (40.5%) were RC followed up (3261 pacemakers, 594 ICDs and 47 implantable loop recorder); the CIED brands were represented as follows: Medtronic 685 (43.3%); St. Jude 180 (11.4%), Boston Sc. 330 (20.8%), Biotronik 318 (20.1%) and Livanova (previously SorinGroup) 69 (4.4%).

During the year 2015 we received a total number of 10396 Tx: 128 (1.2%) red alert; 1944 (18.6%) yellow alert, 141 (1.3%) atrial fibrillation; 403 (3.9%) lost Tx (disconnected transmitters or un-compliant patients for remote interrogation) and 7780 (75%) Tx “OK” with NO events. (Fig. right upper).

The projection model at 2021 with 100% RC patients (break-even) shows a total 25990 Tx: 320 red alert; 1944 yellow alert, 352 atrial fibrillation; 1007 lost Tx and 19459 Tx “OK”. The 2021 monthly Tx would be 2320 (26 red alert; 405 yellow alert, 29 atrial fibrillation; 91 lost Tx and 1769 (75%) Tx “OK”) (Fig. both lower panels)

The RC file analysis was roughly calculated around 3 minutes (116 hours/month); 5.8 hours/business day (Monday–Friday).

Conclusion

The rate of RC followed up CIEDs will inexorably increase by time. The projection management model presented could help to build a sustainable organization.

Ten daily fractions for partial breast irradiation. Long-term results of a prospective phase II trial

Partial breast irradiation (PBI) is an effective adjuvant treatment after breast conservative surgery for selected early-stage breast cancer patients. However, the best fractionation scheme is not well defined. Hereby, we report the 5-year clinical outcome and toxicity of a phase II prospective study of a novel regimen to deliver PBI, which consists in 40 Gy delivered in 10 daily fractions. Patients with early-stage (pT1-pT2, pN0-pN1a, M0) invasive breast cancer were enrolled after conservative surgery. The minimum age at diagnosis was 60 years old. PBI was delivered with 3D-conformal radiotherapy technique with a total dose of 40 Gy, fractionated in 10 daily fractions (4 Gy/fraction). Eighty patients were enrolled. The median follow-up was 67 months. Five-year local control (LC), disease-free survival (DFS), and overall survival (OS) were 95%, 91%, and 96%, respectively. Grade I and II subcutaneous fibrosis were documented in 23% and 5% of cases. No grade III late toxicity was observed. PBI delivered in 40 Gy in 10 daily fractions provided good clinical results and was a valid radiotherapy option for early-stage breast cancer patients.

Prediction of skin dose in low-kV intraoperative radiotherapy using machine learning models trained on results of in vivo dosimetry

PURPOSE

The purpose of this study was to implement a machine learning model to predict skin dose from targeted intraoperative (TARGIT) treatment resulting in timely adoption of strategies to limit excessive skin dose.

METHODS

A total of 283 patients affected by invasive breast carcinoma underwent TARGIT with a prescribed dose of 6 Gy at 1 cm, after lumpectomy. Radiochromic films were used to measure the dose to the skin for each patient. Univariate statistical analysis was performed to identify correlation of physical and patient variables with measured dose. After feature selection of predictors of in vivo skin dose, machine learning models stepwise linear regression (SLR), support vector regression (SVR), ensemble with bagging or boosting, and feed forward neural networks were trained on results of in vivo dosimetry to derive models to predict skin dose. Models were evaluated by tenfold cross validation and ranked according to root mean square error (RMSE) and adjusted correlation coefficient of true vs predicted values (adj-R² ).

RESULTS

The predictors correlated with in vivo dosimetry were the distance of skin from source, depth-dose in water at depth of the applicator in the breast, use of a replacement source, and irradiation time. The best performing model was SVR, which scored RMSE and adj-R² , equal to 0.746 [95% confidence intervals (CI), 95% CI 0.737,0.756] and 0.481 (95% CI 0.468,0.494), respectively, on the tenfold cross validation.

CONCLUSION

The model trained on results of in vivo dosimetry can be used to predict skin dose during setup of patient for TARGIT and this allows for timely adoption of strategies to prevent of excessive skin dose.

Surgery-induced wound response promotes stem-like and tumor-initiating features of breast cancer cells, via STAT3 signaling

Inflammation is clinically linked to cancer but the mechanisms are not fully understood. Surgery itself elicits a range of inflammatory responses, suggesting that it could represent a perturbing factor in the process of local recurrence and/or metastasis formation.

Post-surgery wound fluids (WF), drained from breast cancer patients, are rich in cytokines and growth factors, stimulate the in vitro growth of breast cancer cells and are potent activators of the STAT transcription factors. We wondered whether STAT signaling was functionally involved in the response of breast cancer cells to post-surgical inflammation. We discovered that WF induced the enrichment of breast cancer cells with stem-like phenotypes, via activation of STAT3. In vitro, WF highly stimulated mammosphere formation and self-renewal of breast cancer cells. In vivo, STAT3 signaling was critical for breast cancer cell tumorigenicity and for the formation of local relapse after surgery.

Overall, we demonstrate here that surgery-induced inflammation promotes stem-like phenotypes and tumor-initiating abilities of breast cancer cells. Interfering with STAT3 signaling with a peri-surgical treatment is sufficient to strongly suppress this process. The understanding of the crosstalk between breast tumor-initiating cells and their microenvironment may open the way to successful targeting of these cells in their initial stages of growth and be eventually curative.

Toxicity and cosmesis following partial breast irradiation consisting of 40 Gy in 10 daily fractions

PURPOSE

To assess the toxicity and cosmetic results in breast cancer patients undergoing adjuvant partial breast irradiation (PBI) to a total dose of 40 Gy in 10 daily fractions (4 Gy/fraction).

METHODS AND MATERIALS

Patients affected by early-stage breast cancer were enrolled in this phase II trial. Patients had to be 60 years old and treated with breast conservative surgery for early stage (pT1-T2 pN0-N1a) invasive ductal carcinoma.

RESULTS

77 patients were enrolled. Median follow-up was 18 months. The proposed schedule was well tolerated. One patient reported Grade 3 pain at the site of irradiation. Four (5%) patients experience Grade 2 erythema. Late Grade 2 and 1 fibrosis was observed in 3 (4%) and 14 (18%) patients, respectively. Cosmesis was judged "good/excellent" and "poor" in 75 (97%) and in 2 (3%) patients, respectively.

CONCLUSIONS

40 Gy in 10 daily fractions, 4 Gy/fraction, is a well tolerated regimen to deliver PBI.

Locoregional failure in early-stage breast cancer patients treated with radical mastectomy and adjuvant systemic therapy: which patients benefit from postmastectomy irradiation?

PURPOSE

To assess the locoregional failure in patients with Stage I-II breast cancer treated with radical mastectomy and to evaluate whether a subset of these patients might be at sufficiently high risk of locoregional recurrence (LRR) to benefit from postmastectomy irradiation (PMRT).

METHODS AND MATERIALS

Stage I-II breast cancer patients (n = 150) treated with radical mastectomy without adjuvant irradiation between 1999 and 2005 were analyzed. The pattern of LRR was reported. Kaplan-Meier analysis was used to calculate rates of LRR, and Cox proportional hazards methods were used to evaluate potential risk factors.

RESULTS

Median follow-up was 75 months. Mean patient age was 56 years. One-hundred forty-three (95%) patients received adjuvant systemic therapy: 85 (57%) hormonal therapy alone, 14 (9%) chemotherapy alone, and 44 (29%) both chemotherapy and hormonal therapy. Statistically significant factors associated with increased risk of LRR were premenopausal status (p = 0.004), estrogen receptor negative cancer (p = 0.02), pathologic grade 3 (p = 0.02), and lymphovascular invasion (p = 0.001). T and N stage were not associated with increased risk of regional recurrence. The 5-year LRR rate for patients with zero or one, two, three, and four risk factors was 1%, 10.3%, 24.2%, and 75%, respectively.

CONCLUSIONS

A subset of patients with early-stage breast cancer is at high risk of LRR, and therefore PMRT might be beneficial.

Review: Feto-placental vascularization: a multifaceted approach

Doppler Ultrasound allows the in vivo study of feto-placental hemodynamics. Doppler flow velocity waveforms (FVW's) obtained from the umbilical arteries reflect downstream blood flow impedance, thus giving indirect evidence of vascular villous tree characteristics. Pulsatility Index, which quantifies FVW's, decreases throughout normal pregnancy, indicating decreasing impedance and is often higher in cases of fetal growth restriction (FGR). Different approaches (morphometrical, morphological, mathematical, immunohistochemical and molecular) have contributed to elucidation of which anomalies of the vascular villous tree underlie Doppler findings. 3D ultrasound may be useful in the study of feto-placental perfusion. However, the unsolved question is why developmental villous tree anomalies occur. Crucial to the success of future research is definition of the population studied based on the uniform and correct definition of FGR.

Is three-dimensional power Doppler ultrasound useful in the assessment of placental perfusion in normal and growth-restricted pregnancies?

OBJECTIVES

To investigate three-dimensional (3D) power Doppler ultrasound indices in the assessment of placental perfusion and their relationship to gestational age (GA), placental position and umbilical artery Doppler flow velocity waveform (FVW) patterns in normal and intrauterine growth-restricted (IUGR) pregnancies.

METHODS

Forty-five pregnant women at 23-37 weeks' gestation were studied, of whom 30 had IUGR and 15 were controls. Nine of the IUGR group had normal umbilical FVWs (NED), nine had abnormal patterns but positive end-diastolic velocities (PED) and 12 had absent or reversed end-diastolic velocities (AED). Placental position was assessed as being posterior, anterior or lateral. 3D power Doppler indices related to placental perfusion (vascularization index (VI), vascularization flow index (VFI) and flow index (FI)) were obtained from five different sampling sites in each placenta.

RESULTS

VI, VFI and FI were not significantly dependent on GA or placental position. VI and VFI were significantly lower in PED and AED cases compared with controls, while FI was reduced in the AED group only. VI and VFI showed high variability between different sampling sites within each placenta, while the variability of FI was much lower.

CONCLUSIONS

3D power Doppler sonography can provide new insights into placental pathophysiology. FI, which identifies the most severe cases of placental impairment, appears to be the most reliable index because of its low intraplacental variability. Further studies are needed to verify its accuracy when applied in clinical practice as a substitute for or an adjunct to umbilical artery Doppler studies.

Evidence for a role of TGF-beta1 in the expression and regulation of alpha-SMA in fetal growth restricted placentae

There is evidence that alpha-smooth muscle actin (alpha-SMA) is a protein that plays a pivotal role in the production of contractile forces and it is induced by transforming growth factor-beta1 (TGF-beta1). We have analysed the expression of alpha-SMA, TGF-beta1, its receptor RI and the activator phospho-Smad2 in (a) fetal growth restriction pre-eclamptic placentae characterised by early onset and absence of end diastolic velocities in the umbilical arteries (FGR-AED) and (b) control placentae accurately matched for gestational age. The study was performed by immunohistochemical, quantitative Western blotting, ELISA, RT-PCR and in vitro analyses. We found that TGF-beta1 stimulates alpha-SMA production in chorionic villi cultured in vitro. In addition, we observed that in vivo TGF-beta1 concentration is significantly higher in FGR-AED placental samples than in control placentae and that this growth factor could have a paracrine action on villous stroma myofibroblasts expressing TGF-beta1 receptors and phospho-Smad2. Indeed, we report that alpha-SMA undergoes a redistribution in FGR-AED placental villous tree, i.e. we show that alpha-SMA is enhanced in medium and small stem villi and significantly decreased in the peripheral villi. Our data allow us to consider TGF-beta1 and alpha-SMA as key molecules related to FGR-AED placental villous tree phenotypic changes responsible for increased impedance to blood flow observable in this pathology.

[Follow-up of patients submitted to antireflux laparoscopic treatment. A study by a telephone questionnaire]

OBJECTIVE

As it is difficult to submit patients to instrumental follow-up after laparoscopic treatment of the gastroesophageal reflux disease (GERD), it is not easy to have a complete patients analysis after fundoplication. Telephone questionnaire can be a valid instrument to investigate clinical outcome and patients satisfaction to surgery.

METHODS

This study discusses the results acquired through a telephone questionnaire which has been administered to patients undergoing laparoscopic fundoplication to study postoperative clinical evolution of GERD and satisfaction to surgery through a numerical rating scale from 1 to 10.

RESULTS

Sixty three patients, who had a laparoscopic antireflux procedure at Department of General Surgery of the University of Udine (Italy), answered to telephone questionnaires. Fifty patients (74.9%) reported no symptoms. Patients satisfaction to surgery was 7.93 +/- 2.36. Fifty eight patients (92.1%) would have repeated the operation and 59 (93.6%) would have advised it to a friend suffering of GERD. A significant difference of patients satisfaction between preoperative typical and atypical symptoms has been found (8.43 +/- 2.04 vs. 6.95 +/- 2.71 p < 0.05).

DISCUSSION AND CONCLUSION

Telephone questionnaire is comparable with face to face consultation, allowing to do a correct clinical follow-up, to exclude patients accusing pathological acid reflux after fundoplication; however preoperative symptoms are not so accurate as postoperative symptoms. Their presence giustifies a postoperative oesophageal pH metry.

Investigation of placental stem villi arteries in fetally growth-restricted pregnancies: a multivariate analysis

Thirteen placentas were studied from 5 normal pregnancies and 8 from pregnancies complicated by fetal growth restriction (4 with present, 3 with absent, and 1 with reversed end-diastolic velocities at Doppler interrogation of the umbilical arteries). On immunohistochemically stained slides, the diameter (d) and the wall thickness (t) of the arterial vasculature of the stem villi were measured for a total of approximately 10,000 vessels. A multivariate 'mixed effect model' statistical analysis was performed using d and t as dependent variables and gestational age, delivery mode, fetal and placental weight, the degree of vascular collapse and Doppler blood flow patterns as independent variables. Gestational age, Doppler pattern and the degree of vascular collapse significantly affected both d and t, the mode of delivery influenced d while fetal and placental weights scarcely affected the dependent variables. The above parameters should therefore be taken into account when investigating placental stem vessel morphometry.

Macrophage migration inhibitory factor in human pregnancy and labor

PROBLEM

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine involved in reproduction. Presently there is no information on the possible involvement of MIF in the onset of labor.

METHODS

Macrophage migration inhibitory factor was assayed, by enzyme-linked immunosorbent assay (ELISA), in maternal serum (MS) and amniotic fluid (AF) both, at midtrimester and at term, as well as in cord serum (CS) at birth. Extraembryonic membranes were analyzed by immunohistochemistry.

RESULTS

Amniotic fluid MIF concentrations were significantly higher at term (median 62.10 ng/mL) than at midtrimester (median 20.07 ng/mL) and reached a peak in term labor (median 258.80 ng/mL). The AF/MS ratio varied from a median of 4.34 at midtrimester and 33.7 at term labor. The MS/CS ratio was 0.4. Migration inhibitory factor immunoreactivity was found in different cell layers of the extraembryonic membranes.

CONCLUSIONS

The increased secretion of MIF in AF at term, particularly at term labor, suggests that MIF contributes to the inflammatory events leading to labor.

Quantitative Doppler measures in coiled vessels: investigation on excised umbilical veins

Quantitative assessment of umbilical venous blood velocity with Doppler ultrasound (US) must cope with the coiled structure of the vein inside the cord. Both an experimental and a theoretical approach showed remarkable variations in the insonation angle when the probe was moved along the vein, provided the inclination between the Doppler probe and the cord was kept constant. Inaccurate signal processing, stochastic variability and flow disturbances could, however, mask the influence of the geometry. The above hypotheses were assessed by investigating five cords in vitro a few hours after delivery from normal pregnancies at term. The Doppler signal was sampled at different sites along each cord and the mean Doppler shift estimated by FFT spectral analysis, both directly and through the noise rejection D'Alessio's algorithm, which proved effective in improving the Doppler shift estimate in condition of low signal-to-noise ratio (SNR).

Umbilical Doppler waveforms and placental villous angiogenesis in pregnancies complicated by fetal growth restriction

OBJECTIVE

To test the hypothesis that the characteristics of umbilical artery Doppler flow velocity waveforms in growth-restricted fetuses indicate angiogenesis within placental stem and gas-exchanging villi.

METHODS

We examined 18 placentas from singleton fetuses that were normal structurally and chromosomally but were growth-restricted, preterm, and complicated by preeclampsia. Ten cases with positive end-diastolic flow and eight with absent or reverse end-diastolic flow were compared with six gestational age-matched controls. Sections of villous placenta were examined to determine structural composition (percentage of fibrinoid, intervillous space, and villous tissue), relative proportion of villous types (stem, immature intermediate, and gas-exchanging villi), and the frequency distribution of stem arterial vessel calibers and their branching pattern.

RESULTS

Placentas with positive end-diastolic flow had a significantly (P < .05) higher percentage of gas-exchanging villi (median 69.6%, range 62.5-80.8%) than those with absent or reverse end-diastolic flow (58.3%, 29.9-71.9%) or controls (60.8%, 43.1-65.6%). The gas-exchanging villi from placentas with absent or reverse end-diastolic flow were slender, elongated, poorly branched, and poorly capillarized. There was a progressive trend toward reduced branching of the stem arteries from the controls (median 22%, range 2-38%), through the positive end-diastolic group (17%, 11-20%), to the absent or reverse end-diastolic group (13%, 4-23%).

CONCLUSION

Compared with absent or reverse end-diastolic flow, the placentas from growth-restricted fetuses with positive end-diastolic flow showed a normal pattern of stem artery development, accompanied by increased capillary angiogenesis and terminal villous development. These features suggest an adaptive pathway for the placenta in the face of uteroplacental ischemia.