I am examining the association between chemotherapy and survival among octogenarians with pancreatic cancer who have undergone surgery first - I addition to determining overall survival I want to determine the 5 year survival difference between the chemotherapy and no chemotherapy group:

Relevant code:
stset postopfu90, failure(laststatus)
xi: stcox i.anychemo AGE i.SEX i.racemm ib1.income2m i.insurancem i.hichar1 i.hlos2 i.ajcc8stage i.marginm i.radiationm i.facilitym ib2.region i.timeperiod

sts test anychemo if postopfu90<=60, logrank
ltable postopfu90, by(anychemo) interval(12)

Using the life table I am get overlapping confidence intervals at the 5 year time point, , 7.7% (95%CI [6.1%, 9.6%]) vs. 5.4% (95%CI [4.2%, 6.8%]) for patients who received adjuvant chemotherapy versus those who did not receive chemotherapy, respectively.

However when I perform the logrank test they seem to be significantly different. These results seem contradictory unless I am interpreting the ltable confidence intervals incorrectly?


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