I was reminded of the important topic of occult N2 NSCLC by a comprehensive review that just came out in the Journal of Thoracic Oncology (abstract here) by a friend, thoracic surgeon Frank Detterbeck, who leads the thoracic oncology program at Yale. To review the basics of lymph nodes for lung cancer, N0 means no lymph nodes are involved; N1 means that lymph nodes are involved on the same side as the primary cancer and inside the confines of the lung; N2 nodes are in the middle of the chest, in the mediastinum, which is between the lungs, and on the same side as the main cancer; N3 nodes are involved and on the other side of the mediastinum or above the clavicles. Lymph nodes beyond those points are M1, or metastatic sites, and would be treated as advanced lung cancer. Occult N2 disease is also sometimes called unsuspected or surprise N2 disease as well, and it refers to a surprise upstaging of patients who were thought to have stage I or II NSCLC before surgery, but after the operation, there’s evidence that one or more mediastinal nodes are involved.
For NSCLC, one of the important aspects of staging in patients who don’t have obvious stage IV disease is staging, which is done largely based on scans, but getting tissue from mediastinal lymph nodes is a controversial central feature. However, I think the controversial nature is whether it’s definitely needed or recommended for patients who have what appears to be a stage I lung cancer (in whom the likelihood is so low it’s not definitely needed), or who have imaging that is very, very consistent with cancer in the mediastinum (in whom the likelihood is so high it’s not definitely needed). In between are many potential surgical candidates with larger stage I, or stage II, or not entirely clear but likely stage III NSCLC. In such patients, most well trained thoracic surgeons will try to get tissue with a mediastinoscopy (or other approach, like a transbronchial ultrasound or transesophageal ultrasound, both of which can sample mediastinal nodes) before surgery, because we know that outcomes are not good with surgery alone for such patients, and our standard is to give chemo or chemo/radiation before possibly proceeding with surgery. However, some surgeons don’t do mediastinoscopies, even in cases with enlarged mediastinal nodes or other features that should suggest a high index of concern (you can’t find a fever if you don’t take a temperature). You’ll never lose surgery business if you are willing to do surgery indiscriminately, on people who shouldn’t as well as should have surgery. They may feel that surgery is the most important factor, so it’s worth just pressing forward and dealing with the outcomes later. That’s below the standard of care, but that’s exactly what happens all too often, particularly when surgeons who aren’t specially trained in thoracic surgery do lung cancer resections. What is worse, sometimes during the surgery, they don’t bother going into the mediastinum to look for nodes (this can be done as a mediastinal dissection during the larger operation, if not as a separate mediastinoscopy procedure from the lower neck, going below the sternum (breastbone).
I’ll just emphasize that selection of a well trained and careful thoracic surgeon is extremely important in managing stage I – IIIA NSCLC. A poorly trained or just not motivated surgeon can do a remarkable disservice to a patient and sabotage their best opportunities for good results, and a well trained and thoughtful thoracic surgeon can maximize that. I say that as a non-surgeon. There should be a book on “When Bad Surgery Happens to Good People”. However, even if patients are treated exactly by the book by a great surgeon or oncology team, sometimes you find unsuspected mediastinal disease at the time of the full surgery, even in patients whomay have had a negative mediastinoscopy (which is a sampling, not an exhaustive search for nodes) before surgery. Continue reading
People who have been following my comments know that I am often questioning the wisdom of surgery in patients who don’t fit the usual criteria for resection, which is most commonly pursued in stage I and II NSCLC and is often considered an option for some patients with stage IIIA NSCLC. To provide a very quick review of NSCLC staging, it’s a combination of three factors:
1) Tumor (T) stage — from 1 to 4, going from smallest and easiest to remove to hardest or largest to remove
2) Node (N) stage — from 0 to 3, going from none to further distances from the main tumor
3) Metastasis (M) stage — just a 0 or 1, to reflect whether there has been distant spread outside of the tumor’s lobe of origin
Here is the more detailed staging system, for T stage on one figure, and then for N and M stage in the other.
(Click on image to enlarge)
At the bottom of the second figure are the “Stage Groupings” that define our current (although increasingly refined over time) staging system. You can see that stage, which correlates with prognosis overall, is a product of a combination of how advanced the tumor itself is and measures of likelihood of distant spread, which is nodal stage (correlates with increasing risk of micrometastatic disease and distant spread) and M stage (M1 defining metastatic spread).
A key point is that there are related but distinct risks from a lung cancer. While we are generally most worried about distant spread of SCLC, which is why surgery has no established place in SCLC management, NSCLC can have very differing degrees of local or distant risk. We need to weigh these, potentially also along with the third variable of risk in the brain, as we develop treatment plans:
There’s been several discussions about the potential value of maintenance therapy after the initial chemotherapy for SCLC; I’ve discussed this subject in a prior post, in which I focused on chemo (prior post here) — while the results haven’t been strong enough to lead to a change in standard practice, at least one trial showed a strong trend in the right direction. On the other hand, other studies, such as one recent large one with thalidomide (described in a prior post), looked quite unfavorable for maintenance therapy, at least with this agent. I’ve described the drug zactima (vandentanib, or ZD6474, which inhibits both angiogenesis and EGFR) in yet another post, and it has continued through several large trials, which could potentially lead to its approval in lung cancer if one or more of these is positive. But we’ve already seen the results of one trial of zactima as a maintenance therapy in SCLC. It’s fair to say that this trial won’t lead to it’s FDA approval.
This particular study came out of Canada and was known as the BR.20 trial (the lung trials conducted by the NCI-Canada are numbered BR.__, where BR stands for bronchus). Presented by Arnold and colleagues at ASCO 2007 (abstract here), the study enrolled 107 patients with SCLC, including both limited (about 43%) and extensive disease (57%) who had achieved a complete or partial response to chemo for at least 4 cycles; patients also received chest and/or brain radiation if it was clinically appropriate. Patients were randomized to receive either zactima at 300 mg by mouth daily (a dose that likely inhibits both angiogenesis and the EGFR axis effectively) or a placebo pill as a maintenance therapy after completing chemo (+/- radiation). The focus of the trial was disease-free survival, looking for a delay or prevention of recurrence after treatment.
While zactima was generally well tolerated, there were some side effects that were signficantly increased in the recipients of zactima compared with a placebo, including EKG changes (15% vs. 0%), high blood pressure (21% vs 9%), diarrhea (79% vs. 40%), rash (71% vs. 49%), and abnormal liver tests (46% vs. 15%). Frankly, I’m surprised to see placebo associated with diarrhea in 40% and rash in half of the patients. In both groups, about 55% of patients reported nausea, and about 80% reported fatigue, underscoring the importance of a placebo (because many of us would be concerned about a drug that produces such significant diarrhea, rash, nausea, and fatigue, but perhaps less so if that’s almost entirely just the background of the disease), and the problems caused by advanced lung cancer.
Whether you consider the side effects problematic or not, many people would find it worthwhile if the drug is effective. Unfortunately, there was no benefit to zactima as a maintenance treatment, with an equal progression-free survival, and a nearly significantly worse overall survival for the active drug compared with a placebo:
(Click on image to enlarge)
Although there aren’t many positive things to say here, one interesting thing is that zactima may have been more effective in women, when they picked apart the data (they gave no details). With a small study, this kind of subgroup analysis is very limited, but it’s interesting that the same subgroup trend has also been seen in advanced NSCLC (although we haven’t covered this issue, which is still pretty preliminary, but provocative).
Zactima has looked better in other settings, and maintenance therapy has been more encouraging when chemo was used, so I wouldn’t want to throw out the baby with the bathwater. But this trial at least pretty convincingly tells us that this is the wrong drug, wrong disease, and wrong time. We’re still looking for just the right combination as a maintenance therapy in SCLC.