Are moles with irregular borders always cancerous?

Follow-up. Moles should be photographed and followed by a dermatologist. Irregular borders are not always cancerous. Careful follow-up and observation for redness, ulceration, or pigment spillage are concerning. Please see a dermatologist.
Always concerning. ...But not all progressed to cancer, can be early / pre- stages if you get them checked by a dermatologist as soon as you notice some irregularity / color changes / consistency changes / etc. See a dermatologist or your family dr for evaluation.