Statistical Consulting Services, Data Management Services, Inc. (DMS), National Cancer Institute at Frederick (NCI-Frederick), PO Box B, Frederick, MD 21702-1201, USA. gwa@css.ncifcrf.gov|Statistical Consulting Services, Data Management Services, Inc. (DMS), National Cancer Institute at Frederick (NCI-Frederick), PO Box B, Frederick, MD 21702-1201, USA. gwa@css.ncifcrf.gov|Statistical Consulting Services, Data Management Services, Inc. (DMS), National Cancer Institute at Frederick (NCI-Frederick), PO Box B, Frederick, MD 21702-1201, USA. gwa@css.ncifcrf.gov|Statistical Consulting Services, Data Management Services, Inc. (DMS), National Cancer Institute at Frederick (NCI-Frederick), PO Box B, Frederick, MD 21702-1201, USA. gwa@css.ncifcrf.gov