Toxicology / Carcinogenesis

Biostatistics Branch

The following investigators are involved in Toxicology/Carcinogenesis projects, three examples of which are given below: Gregg Dinse(http://www.niehs.nih.gov/research/atniehs/labs/bb/staff/dinse/index.cfm), Grace Kissling(http://www.niehs.nih.gov/research/atniehs/labs/bb/staff/kissling/index.cfm), Shyamal Peddada(http://www.niehs.nih.gov/research/atniehs/labs/bb/staff/peddada/index.cfm).

Multiple endpoints: Multiple endpoints are often measured in reproductive and developmental toxicity studies. The National Toxicology Program regularly conducts two-year bioassay studies to assess the tumorigenic potential of test agents. Current methods consider each tumor site separately. The Branch developed an approach for joint analysis of data from multiple tumor sites. This approach accounts for within-animal dependency, survival differences between groups and tumor lethality, while also allowing incorporation of historical control information. For other applications, the Branch developed semiparametric latent variable methods that allow joint inferences on dose effects across multiple outcomes.

Multi-level endpoints: The Branch developed methods for assessing overall toxic effects in reproductive experiments when data are both dam-specific, such as litter size, and number of implants and subunit-specific, such as the presence of low birth weight and malformation.

Bioassay evaluation: Members of the Branch participated in the second phase of an Organization for Economic Co-operation and Development validation program for the uterotrophic bioassay. This bioassay was developed to identify the in vivo activity of compounds that are agonists or antagonists of estrogen, which will help to identify compounds as candidates for further testing. The Branch compared two model systems: the immature female rat and the adult ovariectomized rat.

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