Final answer:
Knowing someone's cancer history is critical for guiding their future medical care with appropriate screenings and for assessing the risk of recurrence or a second primary cancer, both of which are crucial for early detection and successful treatment.
Step-by-step explanation:
It is important to find out whether someone has suffered from cancer for several reasons. One of the key reasons is to guide future medical care. A history of cancer can necessitate more frequent screenings for that individual going forward, as well as for certain types of cancer that may have a genetic component, like those influenced by BRCA1 or BRCA2 mutations.
Another reason is to understand the individual's risk of recurrence or of developing a second primary cancer. Diagnosing cancer early improves the chances of successful treatment significantly, and knowing a patient's cancer history is vital for closely monitoring for any signs of recurrence.