. Author manuscript; available in PMC: 2010 Jul 27.

Published in final edited form as: Clin Invest Med. 2009 Jun 1;32(3):E239–E249. doi: 10.25011/cim.v32i3.6113

TABLE 3.

Associations of Country and Socioeconomic Status with Post-Surgical Wait Time to Radiation Therapy in Ontario and California: Women with Non-Metastasized Breast Cancer Diagnosed Between 1998 and 2000

	Ontario							California
	Days Waited				Long Wait^*			Days Waited				Long Wait^*			Ontario vs California
	n	Mdn	90%kv Rate		RR^†	95%	CI ^‡	n	Mdn	90%kv Rate		RR^†	95%	CI ^‡	MDD	RR	95%	CI^†
*Income Within Treatment Groups*
*Node Negative Breast Cancer*
No chemo- therapy	257	82	139	.209				256	50	104	.056				32^¶	3.73	2.23	6.23
High	117	83	127	.169	1.00			146	51	80	.041	1.00			32^¶	4.12	1.86	9.10
Low	140	82	151	.221	1.31	0.77	2.22	110	49	110	.113	2.76	1.08	7.02	33^¶	1.96	1.05	3.66
Chemo- therapy	93	165	270	.321				110	144	225	.225				21^¶	1.43	0.92	2.21
High	52	151	259	.307	1.00			63	142	224	.192	1.00			9	1.60	0.88	2.92
Low	41	175	274	.363	1.18	0.67	2.07	47	147	243	.325	1.69	0.90	3.19	28	1.12	0.68	1.84
*Node Positive Breast Cancer*
No chemo- therapy	41	92	165	.242				24	58	174	.066				34^¶	3.67	0.92	14.56^§
High	21	100	202	.230	1.00			13	55	73	.035	1.00			45	6.57	0.70	61.73^§
Low	20	87	141	.333	1.45	0.55	3.81	11	58	174	.331	9.46	0.73	122.58^§	29	1.01	0.87	1.17
Chemo- therapy	148	205	263	.394				125	164	246	.283				41^¶	1.39	0.99	1.94^§
High	73	209	274	.377	1.00			68	148	236	.170	1.00			61^¶	2.22	1.30	3.79
Low	75	203	261	.407	1.08	0.82	1.43	57	169	249	.337	1.98	1.09	3.61	34	1.21	0.82	1.80

Notes. Receipt of chemotherapy did not differ by country, place or SES. Chemotherapy groups are displayed to distinguish and compare relatively homogeneous clinical groups: node negative or node positive breast cancer, respectively, typically treated with lumpectomy or mastectomy, followed by chemotherapy and radiation therapy or radiation therapy alone. n = number of incident breast cancer cases, Mdn = median, 90%kv = 90^th percentile, RR = rate ratio, CI = confidence interval, MDD = median days difference. Bolded RRs and CIs are statistically significant.

Long wait criterion was six (180 days [node negative disease]) or seven months (210 days [node positive disease]) if radiation therapy was preceded by chemotherapy, four months (120 days) if it was not.

^†

A rate ratio of 1.00 is the baseline.

^‡

Confidence intervals are based on the Mantel-Haenszel chi-square test.

^§

90% confidence interval does not include the null (P < 0.10).

^¶

Median wait differed significantly from baseline (within-country) or between-countries: Mann-Whitney U-test, P < 0.05.