Bronchioloalveolar carcinoma of the lung (BAC) which is advanced and multifocal (more than one area of cancer in a lung or the lungs.) BAC - which is no longer called BAC and instead is a subtype of lung adenocarcinoma - accounts for 5% of lung cancers or less, is more common in non-smokers (a third of patients have never smoked,) in women, and people of East-Asian heritage.