The isotonic fluid depletion and anoxic mucus theory proposes that water- and volume-depleted airway fluid leads to mucus viscosity, subsequent defective ciliary clearance, and a cough that is inadequate to clear the airways. Thus, bacteria in the CF lung are trapped within this viscous airway fluid and multiply within anaerobic growth conditions by changing from a nonmucoid to a mucoid type of organism. 34-36 The transformation of these bacteria to a biofilm-encased form is a means of protection from normal host defenses and antibiotics, making eradication difficult. 37 A neutrophil-dominated airway inflammation is certainly present in CF lung disease, even in clinically stable patients. 31,38
The median age for diagnosis is approximately 58 years, which is about 10 years younger than that for all cancers. There is a wide scope in ages, from teenagers to those in their 70’s or 80’s, with the largest number of patients in their 40’s, 50’s and 60’s with almost the same percentage in the 40-50, 50-60 and 60-70 year ranges. There also appears to be a slightly higher occurrence in females (62%) than males (38%). This gender specific trend could be due to female organ incidence. Due to its tendency for slow growth in a majority of patients, ACC has a relatively indolent but relentless course. Unlike most carcinomas, most patients with ACC survive for 5 years, only to have tumors recur and progress in a substantial number of cases. In a recent long term study conducted at MD Anderson Cancer Center with a study of 160 ACC patients, 89% of the patients survived for 5 years, but that was reduced to 40% at 15 years. These statistical expectations were confirmed in the review of other ACC medical reports as well. This disease specific reduction was due to recurrence rather than failure to achieve local regional control at the primary site. Also, the clinical experience at that institution suggests that two populations of patients with ACC may exist with some surviving just years while others survive decades, with the solid cell histology type possibly being a contributing factor to the more aggressive type. More aggressive growth patterns can occur in some patients for their whole clinical course, while some patients can have a varied experience with both some faster and some slower growing tumors over a more long-term protracted course.