Both overdosing and underdosing are of concern with 5 - FU .
Several studies have shown that the majority of colorectal cancer patients treated with 5 - FU are underdosed based on today 's dosing standard .
Both overdosing and underdosing are of concern with 5 - FU , although several studies have shown that the majority of colorectal cancer patients treated with 5 - FU are underdosed based on today 's dosing standard .