I believe "Sono spiacente" means something similar to "I am sorry" and "Mi dispiace" means something similar to "Forgive me". However, whereas the former is more usual/informal in English, the latter is more usual/informal in Italian. Just like in Brazilian Portuguese. If you Bump into someone in the street you'll would say "(Me) desculpa" in Brazil and "Mi dispiace" in Italy, not "Sinto muito" or "Sono spiacente". In the Angloworld, however, you would say "(I'm) sorry", not "Forgive me" . Nevertheless the words for expressing how you feel (regardless of whether it's not commonly used or not) is I'm sorry / Sono spiacente / Sinto muito, whereas the expression used for asking pardon is Forgive me / Mi dispiace / Me desculpa.
I have a dear friend who was recently diagnosed with cancer. He is now going through the painful and debilitating treatment. I'm wondering how I can express my sorrow about it all. I will try below... Se sbaglia, per favore mi corregga! Grazie!
Mi dispiace, mio amico, a sentire della tua malattia. Spero sinceramente che tu stia bene di nuovo molto presto. Io prego per questo.