Poignant article from the ABC on this serious, yet not discussed about topic.
This is something which affects several people, yet not much information is available about this. Most people will not talk about it, as it is not the main issue. The problem is that this adds up to the rest of the stressors of life. Several relationships break down due to problems during or after cancer diagnosis and treatment.

Worth discussing this in more detail with your cancer specialists.

​Cancer, Sex and Intimacy

One of the possible side-effects of intravenous and tablet based chemotherapy or targeted therapies is diarrhoea. We encourage patients to use Loperamide tablets (Gastro-Stop) to treat and prevent diarrhoea. It works most times, but not always.
Diarrhoea is a adverse effect, which is not managed as well as we should. We have taken huge strides in the areas of vomiting and to some extent nausea, but diarrhoea has still not been tackled well enough.
Some of my patients, who are on chemotherapy, and struggle with diarrhoea (not just the loose bowel motions, but the urgency and uncertainty of the bowel motions) - are scared to go out to public places. Like some of the them tell me - "when you go to go, you got to go now".
I hunted for possible solutions and came across a free App called Flush - Flush app
This has a database of toilet across the city and country towns. I am really not sure how they manage the database and if there is a way to update it in real time, but it surely has helped give some confidence to several of my patients.
Seems like a silly problem?! Ask the person who is struggling with the issue.