With a medical history of breast cancer, the risk class life insurance companies will offer you is going to vary quite a bit between them.
You're generally going to be looking at a substandard table-rating for your life insurance coverage, which means you will pay more than the standard rate for the average person buying life insurance.
The type of cancer, stage of cancer, course of treatment, is treatment completed, how long since the last date of treatment, when your cancer went into remission, and any other medical conditions are some of the factors that will go into the underwriting evaluation of insuring you as a risk for a life insurance company.
In general, most insurance companies will want to wait at least 2 to 5 years from the date treatment is completed for most types of cancer before they will consider offering any life insurance coverage, but this will vary by life insurance carrier and type of cancer.
Guaranteed-issue life insurance plans are available as they do not require a health exam. However, these are "graded" life insurance policies and generally feature a 2-3 year waiting period before providing full coverage (payment of proceeds when death of the insured occurs by illness or injury). If the insured dies under accidental means during the graded period, the life insurance policy will still pay the full death benefit.
Learn more about life insurance for cancer survivors.