A model for the analysis of caries occurrence in primary molar tooth surfaces

Recently methods of caries quantification in the primary dentition have moved away from summary 'whole mouth' measures at the individual level to methods based on generalised linear modelling (GLM) approaches or survival analysis approaches. However, GLM approaches based on logistic transformation fail to take into account the time-dependent process of tooth/surface survival to caries. There may also be practical difficulties associated with casting parametric survival-based approaches in a complex multilevel hierarchy and the selection of an optimal survival distribution, while non-parametric survival methods are not generally suitable for the assessment of supplementary information recorded on study participants. In the current investigation, a hybrid semi-parametric approach comprising elements of survival-based and GLM methodologies suitable for modelling of caries occurrence within fixed time periods is assessed, using an illustrative multilevel data set of caries occurrence in primary molars from a cohort study, with clustering of data assumed to occur at surface and tooth levels. Inferences of parameter significance were found to be consistent with previous parametric survival-based analyses of the same data set, with gender, socio-economic status, fluoridation status, tooth location, surface type and fluoridation status-surface type interaction significantly associated with caries occurrence. The appropriateness of the hierarchical structure facilitated by the hybrid approach was also confirmed. Hence the hybrid approach is proposed as a more appropriate alternative to primary caries modelling than non-parametric survival methods or other GLM-based models, and as a practical alternative to more rigorous survival-based methods unlikely to be fully accessible to most researchers.

Stage IV breast cancer in the community hospital setting: Primary tumor extirpation effect on overall survival

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Background: Publications from academic centers and national cancer databases suggest a survival advantage for women who undergo primary tumor extirpation in the setting of known distant disease. We asked if similar findings exist in a community hospital setting.

Methods: 15,887 patients entered in a longitudinally maintained breast cancer database (encompassing a system network of 13 community hospitals) during 1985-2009 were analyzed for those diagnosed with stage IV disease upon initial presentation. The cohort was divided into those who underwent primary tumor resection, and those who did not. The two subgroups were compared for patient demographics, tumor characteristics, sites of distant metastases, systemic treatment, and overall survival (OS).

Results: 643 (4.05%) presented with an intact primary breast malignancy and synchronous distant metastasis. Median age at diagnosis: 66 years (range 22-96). Median OS: 15 months (range 0-249). 264 (41.1%) patients underwent primary tumor resection as part of first course treatment. On Kaplan-Meier univariate analysis, patients who underwent surgical extirpation of the primary tumor demonstrated improved median OS compared to those who did not (26 vs 10 months; p<0.0001, HR 0.52). Age at diagnosis <50 (p=0.0003, HR 0.65) and oligometastasis to bone (p=0.0002, HR 0.72) were statistically significant predictors of improved OS. Race, primary tumor size, and ER status alone did not influence OS. Those ER+ patients who underwent primary tumor excision in addition to chemotherapy and/or hormonal therapy fared significantly better than those treated with systemic therapy alone (32 vs 17 months; p<0.0001). Chemotherapy 16+ weeks prior to surgery improved OS compared to those who had surgery <16 weeks after starting chemotherapy. While there was no difference with regards to type of resection (partial vs simple vs modified radical mastectomy), clear margins were imperative to optimize OS.

Conclusions: Patients with stage IV breast cancer treated at community hospitals also demonstrate improved OS after primary tumor extirpation, especially in the context of a multimodality approach combining chemotherapy and/or hormonal therapy preceding surgery.

A phase II, multicenter, open-label randomized study of motesanib or bevacizumab in combination with paclitaxel and carboplatin for advanced nonsquamous non-small-cell lung cancer

BACKGROUND

This phase II study estimated the difference in objective response rate (ORR) among patients with advanced nonsquamous non-small-cell lung cancer (NSCLC) receiving paclitaxel-carboplatin (CP) plus motesanib or bevacizumab.

PATIENTS AND METHODS

Chemotherapy-naive patients (N = 186) were randomized 1:1:1 to receive CP plus motesanib 125 mg once daily (qd) (arm A), motesanib 75 mg twice daily (b.i.d.) 5 days on/2 days off (arm B), or bevacizumab 15 mg/kg every 3 weeks (q3w) (arm C). The primary end point was ORR (per RECIST). Other end points included progression-free survival (PFS), overall survival (OS), motesanib pharmacokinetics, and adverse events (AEs).

RESULTS

ORRs in the three arms were as follows: arm A, 30% (95% confidence interval 18% to 43%); arm B, 23% (13% to 36%); and arm C, 37% (25% to 50%). Median PFS in arm A was 7.7 months, arm B 5.8 months, and arm C 8.3 months; median OS for arm A was 14.0 months, arm B 12.8 months, and arm C 14.0 months. Incidence of AEs was greater in arms A and B than in arm C. More grade 5 AEs not attributable to disease progression occurred in arm B (n = 10) than in arms A (n = 4) and C (n = 4). Motesanib plasma C(max) and C(min) values were consistent with its pharmacokinetic properties observed in previous studies.

CONCLUSIONS

The efficacy of 125 mg qd motesanib or bevacizumab plus CP was estimated to be comparable. Toxicity was higher but manageable in both motesanib arms. Efficacy and tolerability of motesanib 125 mg qd plus CP in advanced nonsquamous NSCLC are being further investigated in a phase III study.

Modelling childhood caries using parametric competing risks survival analysis methods for clustered data

Caries in primary teeth is an ongoing issue in children's dental health. Its quantification is affected by clustering of data within children and the concurrent risk of exfoliation of primary teeth. This analysis of caries data of 103,776 primary molar tooth surfaces from a cohort study of 2,654 British children aged 4-5 years at baseline applied multilevel competing risks survival analysis methodology to identify factors significantly associated with caries occurrence in primary tooth surfaces in the presence of the concurrent risk of exfoliation, and assessed the effect of exfoliation on caries development. Multivariate multilevel parametric survival models were applied at surface level to the analysis of the sound-carious and sound-exfoliation transitions to which primary tooth surfaces are subject. Socio-economic class, fluoridation status and surface type were found to be the strongest predictors of primary caries, with the highest rates of occurrence and lowest median survival times associated with occlusal surfaces of children from poor socio-economic class living in non-fluoridated areas. The concurrent risk of exfoliation was shown to reduce the distinction in survival experience between different types of surfaces, and between surfaces of teeth from children of different socio-economic class or fluoridation status. Clustering of data had little effect on inferences of parameter significance.