Determinants of Physical Activity among Patients with Colorectal Cancer: From Diagnosis to 5 Years after Diagnosis.

INTRODUCTION: Physical activity (PA) is associated with higher quality of life and probably better prognosis among colorectal cancer (CRC) patients. This study focuses on determinants of PA among CRC patients from diagnosis until 5 yr postdiagnosis. METHODS: Sociodemographic and disease-related factors of participants of two large CRC cohort studies were combined. Moderate-to-vigorous PA during sport and leisure time (MVPA-SL) was measured at diagnosis (T0) and 6, 12, 24, and 60 months (T6 to T60) postdiagnosis, using the SQUASH questionnaire. Mixed-effects models were performed to identify sociodemographic and disease-related determinants of MVPA-SL, separately for stage I-III colon (CC), stage I-III rectal cancer (RC), and stage IV CRC (T0 and T6 only). Associations were defined as consistently present when significant at ≥4 timepoints for the stage I-III subsets. MVPA-SL levels were compared with an age- and sex-matched sample of the general Dutch population. RESULTS: In total, 2905 CC, 1459 RC and 436 stage IV CRC patients were included. Patients with higher fatigue scores, and women compared with men had consistently lower MVPA-SL levels over time, regardless of tumor type and stage. At T6, having a stoma was significantly associated with lower MVPA-SL among stage I-III RC patients. Systemic therapy and radiotherapy were not significantly associated with MVPA-SL changes at T6. Compared with the general population, MVPA-SL levels of CRC patients were lower at all timepoints, most notably at T6. CONCLUSIONS: Female sex and higher fatigue scores were consistent determinants of lower MVPA-SL levels among all CRC patients, and MVPA-SL levels were lowest at 6 months postdiagnosis. Our results can inform the design of intervention studies aimed at improving PA, and guide healthcare professionals in optimizing individualized support.

Biomarker concordance between primary colorectal cancer and ovarian metastases: a Dutch cohort study.

PURPOSE: The genetic characteristics and mismatch repair (MMR) status of the primary tumor and corresponding metastases in colorectal cancer (CRC) are generally considered to be highly concordant. This implies that either the primary or metastatic tumor can be used for testing gene mutation and MMR status. However, whether this is also true for CRC and their ovarian metastases is currently unknown. Ovarian metastases generally show a poorer response to systemic therapy compared to other metastatic sites. Differences in biomarker status between primary CRC and ovarian metastases could possibly explain this difference in therapy response. METHODS: The study cohort was selected from CRC patients treated in two Dutch hospitals. Eligible patients with CRC and ovarian metastasis who were surgically treated between 2011 and 2018 were included. CRC and corresponding ovarian metastatic tissues were paired. Gene mutation status was established using next-generation sequencing, while the MMR status was established using either immunohistochemistry or microsatellite instability analysis. RESULTS: Matched samples of CRC and ovarian metastasis from 26 patients were available for analysis. A biomarker concordance of 100% was detected. CONCLUSION: Complete biomarker concordance was found between MMR proficient CRC and their matching ovarian metastasis. Biomarker testing of MMR proficient CRC tissue appears to be sufficient, and additional testing of metastatic ovarian tissue is not necessary. Differences in therapy response between ovarian metastases and other metastases from CRC are thus unlikely to be caused by differences in the genetic status.

A propensity score-matched analysis of oncological outcome after systemic therapy for stage IV colorectal cancer: Impact of synchronous ovarian metastases.

The reported incidence of synchronous and metachronous ovarian metastases (OM) from colorectal cancer (CRC) is ~3.4%. OM from CRC are often considered sanctuary sites due to their lower sensitivity to systemic treatment. It has thus been hypothesized that the presence of OM decreases overall survival. Therefore, the purpose of our study was to evaluate the impact of synchronous OM on overall survival in female patients with stage IV CRC treated with systemic therapy alone with palliative intent. The present study used data from the Netherlands Cancer Registry and included female CRC patients with synchronous systemic metastases who were treated with systemic therapy between 2008 and 2018. A subsample was created using propensity score matching to create comparable groups. Propensity scores were determined using a logistic regression model in which the dependent variable was the presence of OM and the independent variables were the variables that differed significantly between both groups. Our study included 5253 patients with stage IV CRC that received systemic therapy. Among these patients, 161 (3%) had OM while 5092 (97%) had extra-ovarian metastases only. Three-year overall survival rates did not show a significant difference between patients with OM compared to patients without ovarian metastases. Moreover, the propensity score-matched analysis showed that the presence of OM in patients treated with systemic therapy for stage IV CRC disease was not associated with decreased 3-year overall survival. However, the results of the present study should be interpreted with caution, due to its observational character and used selection criteria.

Survival of patients with deficient mismatch repair metastatic colorectal cancer in the pre-immunotherapy era.

BACKGROUND: Metastatic colorectal cancer patients with deficient mismatch repair (dMMR mCRC) benefit from immunotherapy. Interpretation of the single-arm immunotherapy trials is complicated by insignificant survival data during systemic non-immunotherapy. We present survival data on a large, comprehensive cohort of dMMR mCRC patients, treated with or without systemic non-immunotherapy. METHODS: Two hundred and eighty-one dMMR mCRC patients (n = 54 from three prospective Phase 3 CAIRO trials; n = 227 from the Netherlands Cancer Registry). Overall survival was analysed from diagnosis of mCRC (OS), from initiation of first-line (OS1) and second-line (OS2) systemic treatment. Cox regression analysis examined prognostic factors. As comparison for OS 2746 MMR proficient mCRC patients were identified. RESULTS: Of 281 dMMR patients, 62% received first-line and 26% second-line treatment. Median OS was 16.0 months (13.8-19.6) with antitumour therapy and 2.5 months (1.8-3.5) in untreated patients. OS1 was 12.8 months (10.7-15.2) and OS2 6.2 months (5.4-8.9) in treated dMMR patients. Treated dMMR patients had a 7.6-month shorter median OS than pMMR patients. CONCLUSION: Available data from immunotherapy trials lack a control arm with standard systemic treatment. Given the poor outcome compared to the immunotherapy results, our data strongly suggest a survival benefit of immunotherapy in dMMR mCRC patients.

Loss of skeletal muscle index and survival in patients with metastatic colorectal cancer: Secondary analysis of the phase 3 CAIRO3 trial.

BACKGROUND: Low skeletal muscle index (SMI) in metastatic colorectal cancer (mCRC) patients is associated with poor outcomes. The prognostic impact of SMI changes during consecutive palliative systemic treatments is unknown. METHODS: This is a retrospective analysis of the phase 3 CAIRO3 study. The CAIRO3 study randomized 557 patients between maintenance capecitabine + bevacizumab (CAP-B) or observation, after six cycles capecitabine + oxaliplatin + bevacizumab (CAPOX-B). Upon first disease progression (PD1), CAPOX-B was reintroduced until second progression (PD2). SMI was assessed by computed tomography (CT) (total 1355 scans). SMI and body mass index (BMI) changes were analyzed for three time-periods; p1: during initial CAPOX-B, p2: randomization to PD1, and p3: PD1 to PD2. The association between absolute and change in SMI and BMI (both per 1 standard deviation) during p1-p3, with PD1, PD2, and survival was studied by Cox regression models. RESULTS: This analysis included 450 of the 557 patients randomized in the CAIRO3 study. Mean SMI decreased during p1: mean -0.6 SMI units [95% CI -1.07;-0.26] and p3: -2.2 units [-2.7;-1.8], whereas during p2, SMI increased + 1.2 units [0.8-1.6]. BMI changes did not reflect changes in SMI. SMI loss during p2 and p3 was significantly associated with shorter survival (HR 1.19 [1.09-1.35]; 1.54 [1.31-1.79], respectively). Sarcopenia at PD1 was significantly associated with early PD2 (HR 1.40 [1.10-1.70]). BMI loss independent of SMI loss was only associated with shorter overall survival during p3 (HR 1.35 [1.14-1.63]). CONCLUSIONS: In mCRC patients, SMI loss during palliative systemic treatment was related with early disease progression and reduced survival. BMI did not reflect changes in SMI and could not identify patients at risk of poor outcome during early treatment lines.

Skeletal muscle mass loss and dose-limiting toxicities in metastatic colorectal cancer patients.

BACKGROUND: Increasing evidence suggests that severe skeletal muscle index (SMI) loss (sarcopenia) is associated with poor overall survival in metastatic colorectal cancer patients, but its mechanisms are unknown. We recently found, using data of the randomized phase 3 CAIRO3 study, that SMI loss was related with shorter time to disease progression and overall survival during first-line maintenance treatment with capecitabine + bevacizumab (CAP-B) or observation and during more intensive capecitabine + oxaliplatin + bevacizumab (CAPOX-B) reintroduction treatment. As a potential risk factor for reduced survival, we explored whether sarcopenia and SMI loss were associated with dose-limiting toxicities (DLTs) during CAP-B and CAPOX-B. METHODS: Sarcopenia status and SMI loss were assessed by using consecutive computed tomography scans. DLTs were defined as any dose delay/reduction/discontinuation of systemic treatment because of reported CTCAE (version 3.0) toxicities at the start or during treatment. Poisson regression models were used to study whether sarcopenia and body mass index (BMI) at the start of treatment and SMI and BMI loss during treatment were associated with DLTs. RESULTS: One hundred eighty-two patients (mean age 63.0 ± 8.8 years, 37% female) received CAP-B, and 232 patients (mean age 63.0 ± 9.0 years, 34% female) received CAPOX-B. At the start of CAP-B and CAPOX-B, 54% and 46% of patients were sarcopenic, respectively. Mean BMI was lower in sarcopenic patients, although patients were on average still overweight (sarcopenic vs. non-sarcopenic at the start of CAP-B 25.0 ± 3.9 vs. 26.7 ± 4.1 and CAPOX-B 25.8 ± 3.8 vs. 27.1 ± 3.8 kg/m2 ). Sarcopenia at the start of CAP-B was not associated with DLTs [relative risk 0.87 (95% confidence interval 0.64-1.19)], whereas patients with >2% SMI loss had a significantly higher risk of DLTs [1.29 (1.01-1.66)]. At the start of subsequent CAPOX-B, 25% of patients received a dose reduction, and the risk of dose reduction was significantly higher for patients with preceding SMI loss [1.78 (1.06-3.01)] or sarcopenia [1.75 (1.08-2.86)]. After the received dose reductions, sarcopenia or SMI loss was not significantly associated with a higher risk of DLTs during CAPOX-B [sarcopenia vs. non-sarcopenic: 0.86 (0.69-1.08) and SMI loss vs. stable/gain: 0.83 (0.65-1.07)]. In contrast, BMI (loss) at the start or during either treatment was not associated with an increased risk of DLTs. CONCLUSIONS: In this large longitudinal study in metastatic colorectal cancer patients during palliative systemic treatment, sarcopenia and/or muscle loss was associated with an increased risk of DLTs. BMI was not associated with DLTs and could not detect sarcopenia or SMI loss. Prospective (randomized) studies should reveal whether normalizing chemotherapeutic doses to muscle mass or muscle mass preservation (by exercise and nutritional interventions) increases chemotherapeutic tolerance and improves survival.

Implementation, participation and satisfaction rates of a web-based decision support tool for patients with metastatic colorectal cancer.

OBJECTIVE: To examine implementation and patients' and providers' participation and satisfaction of a newly developed decision support tool (DST) for patients with metastatic colorectal cancer (mCRC) in palliative setting. METHODS: Our DST consisted of a consultation sheet and web-based tailored information for mCRC treatment options. We conducted an implementation trajectory in 11 Dutch hospitals and evaluated implementation, participation and satisfaction rates. RESULTS: Implementation rates fluctuated between 3 and 72 handed out (median:23) consultation sheets per hospital with patients' login rates between 36% and 83% (median:57%). The majority of patients (68%) had (intermediate)-high participation scores. The median time spent using the DST was 38 min (IQR:18-56) and was highest for questions concerning patients' perspective (5 min). Seventy-six% of patients were (very) satisfied. The provider DST rating was 7.8 (scale 1-10) and participation ranged between 25 and 100%. Remaining implementation thresholds included providers' treatment preferences, resistance against shared decision-making and (over)confidence in shared decision-making concepts already in use. CONCLUSION: We implemented a DST with sufficient patient and oncologist satisfaction and high patient participation, but participation differed considerably between hospitals suggesting unequal adoption of our tool. PRACTICE IMPLICATIONS: Requirements for structural implementation are to overcome remaining thresholds and increase awareness for additional decision support.

Incidence of capecitabine-related cardiotoxicity in different treatment schedules of metastatic colorectal cancer: A retrospective analysis of the CAIRO studies of the Dutch Colorectal Cancer Group.

BACKGROUND: The frequency of capecitabine-related cardiotoxicity has been reported to be low but includes serious adverse events. We conducted a retrospective analysis of the incidence and severity of capecitabine-related cardiotoxicity in different regimens in the treatment of metastatic colorectal cancer in three randomised phase 3 studies. METHODS: We used data of cardiac events reported in the CAIRO, CAIRO2 and CAIRO3 studies of the Dutch Colorectal Cancer Group (DCCG) and analysed the incidence and severity of cardiac events in the different treatment regimens of the trials which all included the use of capecitabine. The following events were included: chest pain, newly diagnosed cardiac ischaemia/infarction, atrial fibrillation, other arrhythmias and heart failure, all graded according to National Cancer Institute Common Toxicity Criteria (NCI-CTC). RESULTS: A total of 1973 patients were included, who received a total of 2461 capecitabine-based lines of treatment. Overall, 5.9% of patients (n = 117) experienced at least one cardiac event, and 2.3% (n = 46) experienced at least one grade ≥3 event. Three patients had two cardiac events. The most frequently observed cardiac event was ischaemia/infarction (2.9%, n = 57), followed by arrhythmias (2.0%, n = 40, including atrial fibrillation in 10 patients), chest pain (0.8%, n = 16) and heart failure (0.4%, n = 7). The highest incidence of cardiac events was observed in patients treated with capecitabine in combination with oxaliplatin and bevacizumab (12%, n = 43). CONCLUSION: We observed capecitabine-related cardiotoxicity in 5.9% of patients, and severe cardiotoxicity in 2.3% of patients. Combination treatment with capecitabine, oxaliplatin and bevacizumab was associated with the highest risk of cardiotoxicity.

Systemic treatment: maintenance compared with holiday.

With the currently available cytotoxic and targeted drugs, metastatic colorectal cancer (mCRC) may be controlled by systemic treatment for a substantial period of time. However, many questions remain about the optimal use of drugs and duration of treatment. The feasibility of chemotherapy-free intervals has been studied in patients with mCRC treated with chemotherapy alone, but the results are conflicting. Current data show that oxaliplatin may be safely interrupted, but they do not allow a firm conclusion on the safety of a full treatment break of chemotherapy. For targeted therapy, continuous inhibition of intracellular signaling by prolonged administration would theoretically be beneficial for efficacy of treatment. Recent data support the use of maintenance treatment with chemotherapy and bevacizumab. No data on the optimal duration of treatment with anti-epidermal growth factor receptor (EGFR) agents are currently available.

Maintenance treatment with capecitabine and bevacizumab in metastatic colorectal cancer (CAIRO3): a phase 3 randomised controlled trial of the Dutch Colorectal Cancer Group.

BACKGROUND: The optimum duration of first-line treatment with chemotherapy in combination with bevacizumab in patients with metastatic colorectal cancer is unknown. The CAIRO3 study was designed to determine the efficacy of maintenance treatment with capecitabine plus bevacizumab versus observation. METHODS: In this open-label, phase 3, randomised controlled trial, we recruited patients in 64 hospitals in the Netherlands. We included patients older than 18 years with previously untreated metastatic colorectal cancer, with stable disease or better after induction treatment with six 3-weekly cycles of capecitabine, oxaliplatin, and bevacizumab (CAPOX-B), WHO performance status of 0 or 1, and adequate bone marrow, liver, and renal function. Patients were randomly assigned (1:1) to either maintenance treatment with capecitabine and bevacizumab (maintenance group) or observation (observation group). Randomisation was done centrally by minimisation, with stratification according to previous adjuvant chemotherapy, response to induction treatment, WHO performance status, serum lactate dehydrogenase concentration, and treatment centre. Both patients and investigators were aware of treatment assignment. We assessed disease status every 9 weeks. On first progression (defined as PFS1), patients in both groups were to receive the induction regimen of CAPOX-B until second progression (PFS2), which was the study's primary endpoint. All endpoints were calculated from the time of randomisation. Analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00442637. FINDINGS: Between May 30, 2007, and Oct 15, 2012, we randomly assigned 558 patients to either the maintenance group (n=279) or the observation group (n=279). Median follow-up was 48 months (IQR 36-57). The primary endpoint of median PFS2 was significantly improved in patients on maintenance treatment, and was 8·5 months in the observation group and 11·7 months in the maintenance group (HR 0·67, 95% CI 0·56-0·81, p<0·0001). This difference remained significant when any treatment after PFS1 was considered. Maintenance treatment was well tolerated, although the incidence of hand-foot syndrome was increased (64 [23%] patients with hand-foot skin reaction during maintenance). The global quality of life did not deteriorate during maintenance treatment and was clinically not different between treatment groups. INTERPRETATION: Maintenance treatment with capecitabine plus bevacizumab after six cycles of CAPOX-B in patients with metastatic colorectal cancer is effective and does not compromise quality of life. FUNDING: Dutch Colorectal Cancer Group (DCCG). The DCCG received financial support for the study from the Commissie Klinische Studies (CKS) of the Dutch Cancer Foundation (KWF), Roche, and Sanofi-Aventis.

Statin use is not associated with improved progression free survival in cetuximab treated KRAS mutant metastatic colorectal cancer patients: results from the CAIRO2 study.

Statins may inhibit the expression of the mutant KRAS phenotype by preventing the prenylation and thus the activation of the KRAS protein. This study was aimed at retrospectively evaluating the effect of statin use on outcome in KRAS mutant metastatic colorectal cancer patients (mCRC) treated with cetuximab. Treatment data were obtained from patients who were treated with capecitabine, oxaliplatin bevacizumab ± cetuximab in the phase III CAIRO2 study. A total of 529 patients were included in this study, of whom 78 patients were on statin therapy. In patients with a KRAS wild type tumor (n = 321) the median PFS was 10.3 vs. 11.4 months for non-users compared to statin users and in patients with a KRAS mutant tumor (n = 208) this was 7.6 vs. 6.2 months, respectively. The hazard ratio (HR) for PFS for statin users was 1.12 (95% confidence interval 0.78-1.61) and was not influenced by treatment arm, KRAS mutation status or the KRAS*statin interaction. Statin use adjusted for covariates was not associated with increased PFS (HR = 1.01, 95% confidence interval 0.71-1.54). In patients with a KRAS wild type tumor the median OS for non-users compared to statin users was 22.4 vs. 19.8 months and in the KRAS mutant tumor group the OS was 18.1 vs. 14.5 months. OS was significantly shorter in statin users versus non-users (HR = 1.54; 95% confidence interval 1.06-2.22). However, statin use, adjusted for covariates was not associated with increased OS (HR = 1.41, 95% confidence interval 0.95-2.10). In conclusion, the use of statins at time of diagnosis was not associated with an improved PFS in KRAS mutant mCRC patients treated with chemotherapy and bevacizumab plus cetuximab.

Optimal duration of systemic treatment in metastatic colorectal cancer.

PURPOSE OF REVIEW: With the currently available cytotoxic and targeted drugs, metastatic colorectal cancer (mCRC) may be controlled by systemic treatment for a significant period of time. However, many questions remain about the optimal use of drugs and duration of treatment. We reviewed the data from clinical trials on the optimal duration of systemic treatment with chemotherapy and targeted therapy in mCRC patients. RECENT FINDINGS: The feasibility of chemotherapy-free intervals has been studied in mCRC patients treated with chemotherapy alone, but the results are conflicting. Current data show that oxaliplatin may be safely interrupted, but do not allow a firm conclusion on the safety of a full treatment break of chemotherapy. For targeted therapy, continuous inhibition of intracellular signalling by prolonged administration would theoretically be beneficial for efficacy of treatment, and has been suggested by retrospectively collected data. Recent data from a prospective study show a clinical benefit for maintenance treatment with chemotherapy and bevacizumab with acceptable toxicity and preservation of quality of life. Survival benefits were seen in selected patient subgroups. No data on the optimal duration of treatment with anti-epidermal growth factor receptor agents are currently available. SUMMARY: There are no definite data on the safety of chemotherapy-free intervals. Data on targeted therapy support the use of maintenance treatment of chemotherapy plus bevacizumab.

Circulating Tumor Cells Count and Morphological Features in Breast, Colorectal and Prostate Cancer.

BACKGROUND: Presence of circulating tumor cells (CTC) in patients with metastatic breast, colorectal and prostate cancer is indicative for poor prognosis. An automated CTC (aCTC) algorithm developed previously to eliminate the variability in manual counting of CTC (mCTC) was used to extract morphological features. Here we validated the aCTC algorithm on CTC images from prostate, breast and colorectal cancer patients and investigated the role of quantitative morphological parameters. METHODOLOGY: Stored images of samples from patients with prostate, breast and colorectal cancer, healthy controls, benign breast and colorectal tumors were obtained using the CellSearch system. Images were analyzed for the presence of aCTC and their morphological parameters measured and correlated with survival. RESULTS: Overall survival hazard ratio was not significantly different for aCTC and mCTC. The number of CTC correlated strongest with survival, whereas CTC size, roundness and apoptosis features reached significance in univariate analysis, but not in multivariate analysis. One aCTC/7.5 ml of blood was found in 7 of 204 healthy controls and 9 of 694 benign tumors. In one patient with benign tumor 2 and another 9 aCTC were detected. SIGNIFICANCE OF THE STUDY: CTC can be identified and morphological features extracted by an algorithm on images stored by the CellSearch system and strongly correlate with clinical outcome in metastatic breast, colorectal and prostate cancer.

Influence of body mass index on outcome in advanced colorectal cancer patients receiving chemotherapy with or without targeted therapy.

PURPOSE: Obesity is associated with an increased risk of development and recurrence of colorectal cancer. However, the role of obesity in advanced colorectal cancer (ACC) patients is unknown. We investigated the effect of body mass index (BMI) on overall survival (OS) in ACC patients receiving systemic treatment in two large phase III studies (CAIRO and CAIRO2). PATIENTS AND METHODS: Treatment data were obtained and analysed from 796 ACC patients who were treated with chemotherapy in the CAIRO study, and from 730 ACC patients who were treated with chemotherapy plus targeted therapy in the CAIRO2 study. Baseline height and weight were used to assign patients to one of the following BMI categories: A (<18.5 kg/m(2)), B (18.5-24.9 kg/m(2)), C (25.0-29.9 kg/m(2)) and D (≥30.0 kg/m(2)). RESULTS: In 796 patients of the CAIRO study a high BMI was associated with better median OS (8.0, 14.9, 18.4 and 19.5 months for BMI categories A, B, C, and D, respectively; P=0.001), and was an independent prognostic factor for OS in a multivariate analysis. BMI was not associated with OS in 730 patients who participated in the CAIRO2 study, although a trend was observed. CONCLUSIONS: These results show that BMI is an independent prognostic factor for survival in patients receiving chemotherapy, but not in patients receiving chemotherapy and targeted therapy. The possible decreased efficacy of bevacizumab in obese patients may explain this discrepant result. The role of BMI in patients receiving targeted therapy should be further tested.

Current questions in the treatment of advanced colorectal cancer: the CAIRO studies of the Dutch Colorectal Cancer Group.

The outcome of patients with advanced colorectal cancer has significantly improved in the past decade because of the development of new treatment strategies. The Dutch Colorectal Cancer Group (DCCG) is a national multidisciplinary clinical research group in The Netherlands. The 3 CAIRO studies of the DCCG address clinically relevant questions in patients with advanced colorectal cancer: the benefit of combination versus sequential therapy, targeting vascular endothelial growth factor and epidermal growth factor receptor, and the role of maintenance therapy. This article presents the outline of these studies and summarizes the current results.

Aging blunts remodeling of the uterine artery during murine pregnancy.

OBJECTIVE: The progressive increase in uterine blood flow (UBF) during pregnancy is accommodated by morphologic changes in the uterine artery (UA) in a process defined as arterial remodeling. This process is accompanied by changes in cytoskeletal architecture of the arterial smooth muscle cells (SMCs) and surrounding extracellular matrix (ECM). Aging reduces flow-induced arterial remodeling. We studied changes in the murine UA during pregnancy and on the effects of aging on the capacity of the UA to remodel in response to pregnancy. METHODS: We determined morphologic and cytologic changes in UA from nonpregnant and pregnant mice aged 12 weeks (young) and 40 weeks (old) and correlated them with their reproductive performance. RESULTS: In young mice, pregnancy induced an early increase in UA wall mass, which preceded lumen widening. These changes were not accompanied by altered densities of elastin and collagen in the ECM of the medial layer. Smooth muscle cell proliferation increased in midpregnancy and was paralleled by a transient decrease in smoothelin and smooth muscle alpha-actin expression. In old mice, these pregnancy-dependent changes in the UA wall were either absent or markedly reduced. Although by day 11 of pregnancy litter size did not differ between both age groups, the number of viable pups in old mice by day 17 of pregnancy and at birth was 25% and 60% less than in young mice. CONCLUSION: Outward hypertrophic remodeling of the UA during pregnancy in young mice is characterized by transient phenotypic modulation and proliferation of SMCs and alterations in the composition of the ECM. In contrast, in older mice, UA remodeling is markedly reduced and accompanied with a loss of viable fetuses near term pregnancy.