coxph won't converge when including categorical (factor) variables

Hello,



[rephrasing and reposting  of a previous question (that was not answered)
with new information]



I have a dataset of 371 observations.

When I run coxph with numeric variables it works fine.

However, when I try to add factor (categorical) variables it returns "Ran
out of iterations and the model did not converge"



Of note, when I restructure all factors to binary variables with dummy and
use glmnet-lasso the model converges.



Here are examples of the code and output (including summary description of
the variables):

maxSTree.cox <- coxph (Surv(time,status)~Chemo_Simple, data=dataset)

Warning message:

In fitter(X, Y, strats, offset, init, control, weights = weights,  :

  Ran out of iterations and did not converge

summary (dataset$Chemo_Simple)

                        Anthra_HDAC       Anthra_Plus       ArsenicAtra
ATRA           ATRA_GO

                0               163                 2                12
0                 2

         ATRA_IDA Demeth_HistoneDAC          Flu_HDAC     Flu_HDAC_plus
HDAC_Clof         HDAC_only

                0                34                37                 4
24                 1

        HDAC_Plus        LowArac       LowDAC_Clof         MYLO_IL11
Phase1

                4                 8                30                 5
5

              SCT    StdARAC_Anthra      StdAraC_Plus          Targeted
VNP40101M

                0                 0                 0                13
23





HELP !!!!


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