I have a 3.5cm spiculated mass in the left breast, is it cancer?

Breast mass: A spiculated mass of that size in your breast requires further evaluation as soon as possible. Cancer is a diagnosis made by a tissue biopsy rather than appearance on an imaging test like a mammogram. The findings may look suspicious on a mammogram, but it's always better to consider all of the diagnostic possibilities and get the biopsy before jumping to any conclusions.

I assume you: Are reporting a mammographic finding. Sounds like you need a biopsy usually done under the direction of ultrasound. Imagin leads to the next step to diagnose, not a diagnosis by itself.