Bronchioloalveolar carcinoma, or BAC, is a subtype of lung adenocarcinoma that has a tendency to progress more slowly, stage for stage, than other types of lung cancer. There are many patients who experience symptomatic and significant progression over months, and rarely patients have a very aggressive and fulminant form of the disease. However, many patients with BAC experience slow growth that raises the risk of potentially overtreating it, with the possibility of detrimental effects from that.
As someone with a particular interest and expertise in BAC, I see the situation with BAC as being similar to the issues we face with prostate cancer. Once a blood test for detecting prostate cancer emerged (prostatic serum antigen, or PSA), it became possible to identify 200,000 men in the US per year who had prostate cancer. The problem is while a huge proportion of men will develop prostate cancer as they get older, many will have an indolent cancer that will not really threaten their survival, and for which treatment with surgery or radiation can have significant long-term side effects. A low grade prostate cancer is well known for being a cancer men can “die with, but not of”. In other words, men can have a prostate cancer that would never directly threaten them, and they can go on to a ripe old age before succumbing to heart disease or another non-cancerous condition.
I haven’t forgotten that this website is about lung cancer and not prostate cancer. My point is that BAC, unlike other forms of lung cancer, brings up the same kind of dilemma. We know that there are some very threatening, aggressive cases of BAC, but many others can be incidentally detected and be very…pokey (not a technical term). So treating BAC like every other kind of lung cancer, which would involve removing a lobe of the lung or perhaps the entire lung, has a real risk of making the treatment worse than the disease. BAC tumors have a tendency to grow slowly over time, and if they’re surgically removed, you can have another BAC come up many years later, unlike other types of lung cancer where you either develop a recurrence within the first 2-3 years or you probably never will. With BAC, you can develop another, likely related BAC lesion 5 or more years later. But it may grow so slowly that it causes no symptoms and is no threat to a person’s life for another 5, 10, 15 years, or perhaps until that person is over 90. But you can make that person symptomatic if you remove enough good lung tissue every time they develop a 5-10 mm BAC lesion. That patient may find themself really missing that good lung tissue that was surgically removed as a lobectomy 5 years ago (perhaps their 2nd lobectomy for BAC) if they develop new BAC in the remaining lung.
A case in point is a 75 year old man with several significant medical problems, including heart disease and diabetes, who had undergone a left upper lobectomy for a small (1.1 cm) BAC 4 years before I met him. In regular follow-up after that, a new right upper lobe nodule was detected, and over the next two years it grew from 5.5 to 7.5 cm. It was in the center of the lung, therefore not easy to biopsy.
(click to enlarge)
While we would standardly want to biopsy this and remove it surgically if it is cancer, and that is definitely a reasonable option, I would just note that at the very slow rate of growth we’re seeing, his other medical problems will likely provde to be the greater threats over the next 5-10 years. This is very likely a recurrence of BAC, but if we watch it, it is likely to remain an asymptomatic small nodule for years to come. That said, removing it is certainly reasonable, although I would strongly urge that if surgery is pursued, a wedge resection to minimize loss of good lung tissue would be my preferred approach over a lobectomy.
Japanese researchers have been the ones who have primarily recognized that well-differentiated BAC lesions are very unlikely to progress into lymph nodes or spread outside of the chest. They have been doing studies with smaller surgeries for BAC, but at this point we don’t have proof that they produce equivalent results to the more extensive standard surgeries we usually do for lung cancer. In the US, there are studies just getting started asking similar questions of whether less extensive surgeries are appropriate for such cases.
At the same time, there are patients with multiple nodules that recur after surgery for BAC. In such cases, surgery is really not feasible for multiple spots, and the cornerstone of treatment is chemotherapy or targeted therapy like EGFR inhibitors/tarceva. However, I often recommend to asymptomatic patients that we follow scans off of treatment initially, generally every 3-6 months to start with. In many of my patients, they feel completely well and show minimal change on scans for years at a time, without any treatment. We could start chemo or tarceva immediately, but I wouldn’t want to waste a potentially valuable treatment, still likely to have some side effects, if a patient may go years before needing any treatment. Since tumors tend to become resistant to all of these therapies after months or years at most, I’d rather keep them available for when things are growing and we really need them.
The observation approach isn’t right for every patient. I wouldn’t want my patient to be disabled by anxiety due to “not doing anything” about their cancer. But BAC, unlike most other lung cancer types, has the potential to be a chronic disease, and that means that it makes sense to consider when to use the finite resources of effective treatments available, and also to see whether it will actually impact a patient’s health in the context of their entire clinical picture.
posted by Dr. West @ 12:15 am link to this post
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April 10th, 2008 at 5:42 am
Dr. West,
Thanks for th info and the quick reply!
Linda
April 9th, 2008 at 5:51 am
Linda,
Frankly, my leading suspicion would be that all of your lung nodules represent the same process, but some of those nodules act more like the adenocarcinoma part of the name, and some act more like the “with BAC features” part of the name. We know that adeno w/BAC features is a spectrum, and we often see that people have multiple nodules, some of which grow at a clinically meaningful pace, and some can grow at an amazingly slow pace. To me, that sounds exactly like your situation.
I think it makes sense to follow nodules that haven’t been growing and treat with a systemic (whole body) therapy on an “as needed basis” in the event of progression of several nodules at a time (multifocal progression). The thing I’d be concerned about it that this IS a multifocal issue right now, and I don’t think you could be confident that surgery will end the issue. Because of that, there’s a danger in doing multiple surgeries over time and running out of good lung tissue when you take out one of these every few years with some surrounding good lung, especially if you do a lobectomy each time.
-Dr. West
April 9th, 2008 at 3:13 am
I am in the interesting position of having 2 primary lung cancers: an adenocarcinom with bac features, 2.5cmm, discovered on routine chest xray last April(upper left lobectomty in June) and several small nodules throughout both lungs discovered on CAT scan workup. The ones in my lower left lung were removed during the surgey and were biopsied as pure non-mucinous bac. All nodes and margins were clean.
So it was wait and see and have a CAT scan every 3 to 4 months. Okay until Feb. when a new 1 cm mass appeared in lower left lobe. Was unchanged 6 weeks later.
So I’m scheduled for surgery to remove the new mass. What I’m wondering about is post-surgery. Yes, if this turns out to be one of the bac guys who got a little feisty, I guess I’m back to watchful waiting. What if it’s an adenocarcinoma like the original 2.5cm one? Doesn’t this mean that despite clean nodes and margins, some cells are floating around out there?
Should I be considering some sort of chemo?
I should add that I’m 63, female, ex-smoker (quit 30 yrs ago, smoked a pack a day for 15 years before that), in perfect health (if you don’t count the lung cancer) and had negative brain MRI and bone scans last July.
Just wondering about your thoughts on this. Part of me thinks let’s zap those damn cells with everyhting we’ve got and part of me thinks, I just want to go back to work after surgery and I’ll deal with whatever else arises when and if it does.
Thanks,
Linda
April 15th, 2007 at 3:38 pm
There are lots of different kinds of CT scans, and a screening CT scan has a pretty minimal amount of radiation associated with it. I am not an expert on that, but my view is that the risk of cumulative radiation problems from screening CTs is very unlikely to ever be clinically relevant, and even if it is, it’s likely to be an issue decades from now. There’s usually a lag of 20-30 years between radiation exposure and “secondary cancers” from that, but that applies far more to significant radiation exposure like atomic bombs or treatment levels of radiation than routine scans. Overall, I would say that the risk of missing a clinically relevant lung cancer is much greater than the more theoretical risk of a cancer or other problem from multiple CT scans over several decades.
At 73, I do think there’s a real risk of overtreating a nodule if it grows from 8 to 9 mm over a couple of years. While I was specifically talking about well-differentiated BAC lesions, I’ve mentioned that the clinical behavior/imaging changes are much more important for my recommendations than the pathology results. Your case certainly sounds like one that isn’t very clinically threatening, but the fact that you’ve had a lung cancer puts you at higher risk of developing another in the future. After four years, the risk of a new cancer exceeds the risk of the old one returning.
I am not sure about the increased risk of adenocarcinoma of the lung and asbestos. There are 20,000+ never-smokers in the US each year who develop lung cancer without any asbestos exposure, so it’s not the only explanation.
I would be more inclined to call you a 5-year survivor, but it’s not like there are any official rules or terminology for your situation. I think it’s fair to say that your long follow-up gave a fair sense of the pace of the cancer, which was very slow.
Anyway, the core of my answer is that I would estimate the risk of not doing CT scans to be greater than the risk of doing them, even though I agree that the clinical behavior of your cancer was pretty favorable.
-Dr. West
April 15th, 2007 at 12:04 pm
Dr West,I will give a brief description of my lung cancer history and than a few questions.
In 1996 due to a car accident I had a ct scan and 2 nodules were found one in each lung.I was told to have another scan in 6 months.I did not follow orders, as I was not smoker,but I did have another 3 years later in /99.I showed little change and the left lung nodule disappeared and a 6 mo. follow up recommended.Again I waited 1 yr.to 2000 and again no changes.I also had a PET scan in 2000 and nothing showed up.A 6 mo follow up was recomended.I had my third CT now in 2002 and a slight growth was noticed.
In July 2002 I had surgery at MGH and a wedge excision was done. Lab report:Adenocarcinoma,poorly differentiated,mixed acinar and BAC subtypes 1.2 X 0.8 cm Resection margins are free of tumor.No vascular invasion,no pleural invasion.
I have had only ct scans evey 6 mos since surgery.
My questions:
I am now 73, feel great and am very active,swimming,competitive tennis and work outs in the gym 2/3 times a week..After 5 years this July 1st do I need to keep getting CT scans with all its radiation?I must have had a 15/20 ct scans for varrious reasons but mostly for LC.
I was never a smoker but was exposed to asbestos from auto parts, like brakes.My doctors believe this caused my LC.Does this make it more or less likey to reappear?
Am I a 5 year survivor or a 11 year survivor from the first time a nodule was spotted in my lung by the CT scan ‘96?
Seeing my first nodule was slow growing,if another shows up in the lung should it be removed or just watch it with more CT scans? And how many CT scans can the body take before it does more harm than good?
TIA and any other advice,is much appreaciated.
Peter Reiss