艰难的治疗用英文怎么说

艰难的治疗可以用英文表示为 "difficult treatment" 或 "arduous treatment."

"Difficult" 是形容词，意思是困难的、艰难的。

"Arduous" 也是形容词，意思是费力的、艰苦的。

例句：

The patient has been through a difficult treatment process for their cancer. (这位病人经历了艰难的癌症治疗过程。)
The arduous treatment for the rare disease left the patient exhausted. (这种罕见疾病的艰苦治疗使病人精疲力竭。)