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Potential Surgery for Locally Advanced NSCLC: Assessing Loca

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Potential Surgery for Locally Advanced NSCLC: Assessing Local vs. Distant Risk

July 27th, 2012 - by Dr. Jack West

http://blog.lungevity.org/2012/07/27/lo ... stant-ris/

The staging system for lung cancer provides a general outline not only of prognosis but of the general approach to treatment. Within our current definitions, surgery is most readily recommended to patients with stage I or II NSCLC, somewhat more sparingly and debatably for patients with stage IIIA NSCLC, and far less commonly for patients with stage IIIB disease, who often still have a potential to be cured, but not typically with surgery. To provide a very quick review of NSCLC staging (using a system called TNM 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

The groupings are of which combinations lead to which stage are somewhat complex. However, the rule is that stage is a product of a combination of how advanced the tumor itself is, which really reflects the probability of local spread (in the area around the main cancer), and measures of probability (or certainty) of distant spread, which is reflected by nodal stage (correlates with increasing risk of micrometastatic disease and distant spread) and M stage (M1 defining metastatic spread, i.e. proven distant disease).

A key theme here is that there are related but distinct risks from a particular lung cancer. Unlike SCLC, which has a very high propensity to spread early (which is why surgery is rarely used for SCLC and chemo is nearly always recommended as a centerpiece of treatment), NSCLC can have very differing degrees of local or distant risk. In developing the optimal treatment plan for a given person and their particular cancer, we need to weigh these different risks, potentially also along with the third variable of risk in the brain:

The main point is that some patients have higher risk of local recurrence and lower risk of distant recurrence, while other patients have a much higher risk of distant recurrence than local disease. For instance, stage IIIA NSCLC includes T3 (tumor > 7 cm) N1 (positive node(s) within the lung) disease, as well as T1 (tumor <3 cm) N2 (nodal disease between the lungs, more toward the same side as the main tumor), and also T4 (invading important chest structures like the aorta or carina, the split at the bottom of the trachea) even with no nodal disease. But the person with T4 N0 nSCLC has a considerably lower risk of distant recurrence than someone with N2 disease. Higher T stage predicts greater risk of local/regional recurrence, while higher N stage predicts higher risk of micrometastases and distant recurrence.

This has some significant implications in considering individualized, sometimes more heroic treatments for patients with locally advanced NSCLC, for whom surgery might be especially challenging or even infeasible. Stage for stage, pushing the limits of treating an area of residual, viable tumor makes far more sense for someone with little or no nodal spread (let alone distant, metastatic spread) but a big, persistent, or just poorly located mass than for someone with a cancer that spread to many different lymph nodes, even if they are the same stage of cancer.

Time can also be an important ally in determining risk of spread. Because we definitely don’t want someone to undertake the risks of surgery or radiation to an area of active disease only to have it appear in other places at the next CT scan, we hope to have some confidence that a cancer has a low propensity to spread. Seeing a cancer that has grown in the same spot, if someone happens to have a comparison film from a year or two ago (or sometimes longer), without spreading to other places in that interval gives us good reason to expect that local therapy will be curative and that the risk of distant spread is lower — perhaps low enough to recommend against adjuvant chemotherapy for someone who isn’t an ideal candidate for it or is dubious about its value.

These are some of the ways in which we think about local vs. distant risk for a given cancer. It’s a particular characteristic for each one, and the pattern of spread thus far, over a given time line, is a very helpful clue when there is room for individualizing the treatment plan.

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