Table 1. Regression analysis for treatment effects on tumor growth.

Treatment	n	Growth curves, V(t)	r	Tumor doubling time (d)	Growth delay (d)
PBS	11	ln(V)=0.10t+5.50	0.99	6.6 (6.4–6.9)	0 (0–2.0)
PBS+2 Gy	11	ln(V)=0.08t+5.52	0.98	8.5 (8.2–9.0)*	3.5 (0.1–7.0)
VNP pRZ	8	ln(V)=0.08t+5.40	0.98	8.3 (7.9–8.7)*	4.5 (1.3–7.6)
VNP pRZ+2 Gy	6	ln(V)=0.07t+5.44	0.98	10.4 (10.1–10.8)*,†	8.6 (5.3–12.0)*
VNP pRT	11	ln(V)=0.09t+4.92	0.97	7.9 (7.6–8.2)*	9.1 (6.7–11.6)*
VNP pRT+2 Gy	8	ln(V)=0.06t+5.07	0.95	12.2 (11.7–12.8)*,†	19.0 (15.0–23.1)*,†

Data are listed as means with their 95% confidence intervals in parentheses. Treatments of Balb/c mice with 21-day 4T1/red tumors were performed using intravenous injections of PBS (control), 100 000 cfu g⁻¹ VNP20009 pRecA_ZsGreen (VNP pRZ), or 100 000 cfu g⁻¹ VNP20009 pRecA_TRAIL (VNP pRT). Regression growth curves summarise volume (V, mm³) dependence on time (t, days) from initial treatment, with correlation coefficients indicated by r. Primary treatment dosing was at day 0, with or without 2 Gy irradiation at day 2. Tumor doubling time was derived from exponential growth curves. Growth delay was determined by assessing the time interval to 1000 mm³ compared with the PBS control.

^*P<0.05 compared with PBS.

^†P<0.05 compared with PBS and 2 Gy irradiation.