The Tarot card associated with Cancer is The Chariot (forward movement and ambition). If you pull it in a reading, you know that control and progress (either too much, or not enough) is an issue. Sometimes this card can indicate a literal relocation. The version I included here (from the Tarot of the Magical Forest deck published by Lo Scarabeo) nicely shows its power. It often indicates something that's overwhelming.
This reminds us that Cancer is a Cardinal (initiating) sign. It likes to be cozy, but feelings are paramount. If those feelings are not being satisfied, Cancer will do something about it. Mastery of emotions is crucial; the Chariot is about controlled movement. Going after something and having a purpose.
As the energy builds in Cancer, this card is a reminder to let your emotions fuel you, but not run you into the ground.