The new, 7th Edition of the TNM (tumor, nodes, metastases) staging system for lung cancer came into use earlier this year and has led to changes in the staging of about 15% of lung cancers compared with what they'd have been staged as under the 6th edition. Under this new system, some patients have been upstaged: patients with 2.2 cm node-negative lung cancer are now considered T1b instead of T1a, and patients with a 5.5 cm node-negative cancer have an overall stage of IIA instead of 1B. On the other hand, others are downstaged, so that people with additional nodules in the same lobe as a primary tumor are now stage IIB instead of IIIB, and those with other nodules in different lobes of the same lung are now considered stage IIIB instead of stage IV.

The problem is that this leads to a gulf between the evidence produced with an older staging system and how to direct treatment for people today. The staging system is designed to stratify the prognosis -- how long we expect a group of people to live -- for people with lung cancer; it isn't specifically designed to define the treatment that people should receive, though there are general guidelines that emerge largely based on stage. Nevertheless, a recent publication in the Journal of Thoracic Oncology confirms what I've been seeing pretty commonly from referrals to my fractive or comments here on the discussion forum. Clinicians are very often changing treatment recommendations based on the new stage, even though the biology of the cancer in 2010, under the 7th edition of the lung cancer staging system, is the same as it was under the 6th edition. Specifically, 77% of physicians surveyed at a series of recent lung cancer meetings indicated that they would change the treatment recommendations for a patient based not on the underlying characteristics of the cancer but by the overall stage that this translated as.

In some cases, this makes some sense, since the 6th edition had some shortcomings that the 7th edition has improved on, now bringing in line a new stage that fits better with an appropriate treatment strategy. For instance, the staging of a satellite nodule in the same lobe as a main primary lung tumor being classified as a stage IIIB NSCLC (usually not treated with surgery) in the 6th edition was just goofy: it made far more sense to do a lobectomy in this situation if a person has otherwise resectable disease. Also, malignant pleural effusions were categorized as stage IIIB and not stage IV, requiring the inelegant term "wet IIIB" that was generally appropriately paired with stage IV because it represents systemic spread of the cancer. In the 7th edition, a malignant pleural effusion is now categorized as stage IV(a) disease.

But I've also seen much more questionable if not completely dubious misinterpretations, such as patients with a 2.5 cm node-negative NSCLC tumor recommended for adjuvant chemotherapy after resection because it's now called stage T1b, even though this would have been T1a under the staging system that was followed during the time of the adjuvant therapy studies that actually established the survival benefit of adjuvant chemotherapy. In fact, these studies have shown either no benefit or even a strong trend toward a harmful effect of chemo in patients with node-negative cancers smaller than 4 cm. On the other end of the staging spectrum, having lung nodules throughout the right lung isn't an indication for a pneumonectomy even though it's classified now as stage IIIA. This is really a by-product of the fact that most of these patients with this pattern have a bronchioloalveolar carcinoma (BAC) subtype of lung cancer that tends to be more indolent. It doesn't mean that surgery is the right treatment.

Bear in mind that there is now mounting evidence that patients with an EGFR mutation and advanced NSCLC have a median survival that is quite a bit better than other people with advanced NSCLC and is even superior to that seen in a broad population of patients with stage IIIA NSCLC. If future staging systems eventually incorporate molecular markers, a prognosis-based staging system could put metastatic NSCLC with an EGFR mutation in the same class as other stage IIIA NSCLC disease, but it shouldn't be treated the same way.

The key point is that stage alone doesn't dictate the appropriate treatment. The new staging system is a more refined estimate of prognosis, but it didn't change the biology of the disease, so treatments can't be offered as a "color by numbers" approach. The role for individualized recommendations remains central, rather than just having a template that all patients with a certain stage of lung cancer should follow a particular treatment path.