Table 1.

Study Participants Available by Year of Follow-Up and Age at Breast Cancer Diagnosis

Year of Follow-Up	Age < 50 Years (n = 199)		Age 50-79 Years (n = 366)		Age 80+ Years (n = 84)		All Participants (N = 649)
	No. of Participants	%	No. of Participants	%	No. of Participants	%	No. of Participants	%
Eligible at start of follow-up*	196	100	354	100	81	100	631	100
Start of year 2	181	92	338	95	77	95	596	94
Start of year 3	164	84	308	87	65	80	537	85
Start of year 4	138	70	256	72	39	48	433	69
Start of year 5	133	68	238	67	34	42	405	64
End of year 5	119	61	219	62	24	30	362	57

^*Eighteen enrolled participants were found to be ineligible at start of follow-up because there was no unaffected comparison side and lymphedema could not be evaluated, including 17 participants who had simultaneous bilateral mastectomies at the reference date (histologic confirmation of breast cancer diagnosis) and one participant with a pre-existing size difference affecting the entire arm. Among the 631 remaining eligible study participants, an additional six participants recalled a size difference in their hand, lower arm, or upper arm that preceded their breast cancer diagnosis. Five of these six participants had pre-existing size differences in only one part. These pre-existing size differences were not used to calculate incidence of lymphedema, although these six women contributed to estimating incidence rates based on the parts of the arm that were the same at diagnosis.