Am I a Candidate for Surgery?

Review and discussion of tumor stage as a prognostic factor for the outcome of surgery for mesothelioma

“I refuse to join any club that would have me as a member.”
Groucho Marx

Prior to diagnosis no one wants to join the club of “candidates for mesothelioma surgery,” but after reviewing treatment options many patients decide that surgery is their best choice. [Please see our article, “Why Operate?” for a discussion of surgical benefits regarding pleural mesothelioma.]

Doctors have to balance the possibility of extending life with the risk that the patient will die from aggressive and invasive surgery. They also have to balance the possibility of extending life with the possibility that even after successfully removing all visible tumor, the patient will quickly succumb to the disease anyway.

Patients have to make a similar analysis. Will I die on the operating table or shortly thereafter? Will surgery extend my life without making survival so painful and debilitating that my quality of life and that of my family is nil?

The patient resolves those questions by consulting with the surgeon and the family. The doctor, however, resolves them by looking at prognostic factors. Those factors help the surgeon estimate the chance that the surgery will do more good than harm. Before deciding on surgery, patients should know what the factors are that most strongly influence the success or failure of surgery.

Prognostic factors

Prognostic factors can help doctors and patients choose a treatment plan. Patients in the best prognostic groups may decide to choose aggressive or experimental therapy, or they may prefer a period of observation before selecting a treatment option.

The earliest studies tried to come up with a list of factors that would predict the best survival in meso patients who underwent surgery. In general, the more a cancer tumor has progressed from its early stages to its late stages, the worse the outcome for the patient. Mesothelioma surgeons needed a way to measure, or stage the tumor so that they would have a uniform system for describing the tumor’s progress, which in turn would allow them to look at the tumor’s stage and assess its impact on survival after surgery.

By 1995, the International Mesothelioma Interest Group had come up with a proposed tumor staging system in order to replace the scattered and inconsistent systems—five of them—that had been around since 1976.

This staging system is based on the relationship between the size of the tumor, the type of tumor, whether or not the nearby lymph nodes have become cancerous, whether the cancer has metastasized to other regions, and how these factors relate to the patient’s survival after surgery. However, it’s very important to note that the IMIG staging system is useful only for patients considering surgery. For patients only undergoing chemo or radiation, factors such as poor performance status, non-epithelial tumor, male gender, and other factors are more important for their prognostic value.[1] In fact, performance status, or the overall health of the patient as measured by lung function and lung reserves, is the most important prognostic factor for nonsurgical treatment of pleural mesothelioma.[2]

Tumor stage as a prognostic factor for surgical candidates

But back to surgery. For those who will undergo EPP or PD surgery, the stage of the tumor as measured by the IMIG system does play a role in predicting the outcome of the operation. How much of a role? One of the earliest studies to evaluate the IMIG system found that tumor stage, tumor type, and type of surgery were the only factors that had a significant influence on overall survival.[3]

In a follow up study, the same authors found that the significant factors were tumor stage, type of tumor, gender, and whether some additional therapy such as chemo or radiation had been tacked on to the surgery.[4]

The IMIG tumor staging system works like this. It takes three factors, the primary site tumor (T), the regional lymph nodes (N), and the presence/absence of distant metastasis (M), and combines them to come up with a stage for the tumor.

The tumor is assigned values ranging from T0, where there is no evidence of primary tumor, to T4, where the tumor has invaded the chest wall and involved ribs, the peritoneal cavity, spine, or heart. Lymph nodes are assigned values ranging from N0, where there is no regional lymph node involvement, to N3, where the cancer has involved the opposite side mediastinal, internal mammary, or hilar lymph nodes and or same side or opposite side supraclavicular or scalene lymph nodes. Distant metastasis is M0 or M1, indicating presence or absence of spreading tumors remote from the primary site. The complete descriptive list of T, N, M and their varying stages is published in detail by the British Thoracic Society and Society of Caddiothoracic Surgeons of Great Britain and Ireland Working Party.[5]

The IMIG system then combines these factors to come up with a stage. For example, Stage 1 is T1 N0 M0, which means that the tumor involves the same side pleura of the chest wall, with or without focal involvement of the pleura on the outer side of lung; there is no involvement of regional lymph nodes; and there is no evidence of distant metastasis.

Stage I and II tumors “have a much more favorable survival than was previously assumed for malignant mesothelioma, and suggests that surgical resection and adjuvant therapy may improve survival.”[6] Recent surgical studies update some of these findings, indicating that with regards to surgical outcomes, staging is a significant independent prognostic factor.[7]

Conclusion

When trying to decide whether or not to undergo PD or EPP, it is important to know the staging of the tumor. However, other factors in addition to the tumor’s stage can provide prognostic information about the outcome of the surgery. And although tumor staging can be a significant prognostic factor for surgery, it is a much less important predictive factor for nonsurgical treatments

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[1] Steele J.P. et al. Prognostic factors in mesothelioma. Lung Cancer, 2005; Jul:49

[2] Pass H.I. et al. Oncology: An Evidence-Based Approach, Chapter 38: Therapy for Malignant Pleural Mesothelioma, Springer Verlag 2006; p. 627

[3] Rusch V. and Venkatraman E. The importance of surgical staging in the treatment of malignant pleural mesothelioma. J Thorac Surg, 1996; 111:815

[4] Rusch V. and Venkatraman E. Important prognostic factors in patients with malignant pleural mesothelioma, managed surgically. Ann Thorac Surg, 1999; 68:1799

[5] Guidelines on the selection of patients with lung cancer for surgery, Thorax, 2001; 56:98

[6] Id., Rusch 1999

[7] Okada M. et al. Radical surgery for malignant pleural mesothelioma: results and prognosis. Interact Cardiovasc Thorac Surg, 2008; 7: 102-6