Table 2. Illustration of the cumulative incidence of breast cancer-specific mortality for the breast cancer data set using the competing risk approach.

(a) A subset of breast cancer patientsa
Patient number	Follow-up time	Status	BC status
1	7	Alive	C
2	10	Dead-BC	E
3	14	Alive	C
4	16	Dead-BC	E
5	18	Dead-Other	CR
6	23	Dead-BC	E
7	24	Alive	C
8	26	Dead-Other	CR
9	27	Dead-BC	E
…
(b) An illustration of estimating cumulative incidence accounting for competing risk for the subset of breast cancer patients listed above (a)
Step 1
Time interval (tj)	# at risk (nj)	# of events (dj)	Survival probability ((nj−dj)/nj) (%)	Overall survival (S(tj)) (%)
0–	305	0	100	100
10–	304	1	99.7	99.7
16–	302	1	99.7	99.3
18–	301	1	99.7	99.0
23–	300	1	99.7	98.7
26–	298	1	99.7	98.3
27–	297	1	99.7	98.0
…
Step 2
Time interval (tj)	# at risk (nj)	# of events (dj1)	Failure probability (h1(tj)) (%)	Survival up to time tj (S(tj−1)) (%)	Incidence (h1(tj)*S(tj−1)) (%)	Cumulative incidence (I(tj)) (%)
0-	305	0	0	100	0	0
10-	304	1	0.3	100	0.3	0.3
16-	302	1	0.3	99.7	0.3	0.6
23-	300	1	0.3	99.0	0.3	0.9
27-	297	1	0.3	98.3	0.3	1.2
…

C=censored; E=event; CR=competing risk event.

^aThe follow-up time (in months), event status (dead due to breast cancer, dead due to causes other than breast cancer, or alive), and breast cancer death status (event if patient died due to breast cancer, censored otherwise).