使用 survival package

>km<-survdiff(formula = Surv(overallsurvival, status) ~ antt[,54],data=antt)
>km
Call:survdiff(formula = Surv(overallsurvival, status) ~ antt[, 54],data = antt)
N Observed Expected (O-E)^2/E (O-E)^2/V
antt[, 54]=C 77 36 41.43 0.711 5.46
antt[, 54]=mut 21 12 6.57 4.484 5.46
Chisq= 5.5 on 1 degrees of freedom, p= 0.0195

在最后面有个p=0.0195 如何把这个P值提取出来？
> summary(km)
Length Class Mode
n 2 table numeric
obs 2 -none- numeric
exp 2 -none- numeric
var 4 -none- numeric
chisq 1 -none- numeric
call 3 -none- call  
> str(km)
List of 6
$ n : 'table' int [1:2(1d)] 77 21
..- attr(*, "dimnames")=List of 1
.. ..$ groups: chr [1:2] "antt[, 54]=C" "antt[, 54]=mut"
$ obs : num [1:2] 36 12
$ exp : num [1:2] 41.43 6.57
$ var : num [1:2, 1:2] 5.4 -5.4 -5.4 5.4
$ chisq: num 5.46$ call : language survdiff(formula = Surv(overallsurvival, status) ~ antt[, 54], data = antt)- attr(*, "class")= chr "survdiff"

km 为包含6个成分的list变量
使用km$n,km$obs,km$exp,km$var,km$chisq, km$call 均得到不到p 值 。

求大神赐教！