Cancer is a sign very much associated with home. House, apartment, land, garden, home town, homeland. I often find crab shells in the water, which are reminders that Cancer carries her/his 'home' as part of himself or herself.
The Third House, at its core, is about being heard and read. Thus we go into areas like literacy, translation, speech impediments, deafness, public speaking, and of course vision, as one has to read, in order to translate and transmit.
The Second House is about everything you earn, own or owe. Money, credit cards and shopping are Second House matters.
The first house is about appearances. You can be the real you, away from what you wear, and how you use your body language, and how you are profiled. But - image matters.