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Cancer of the Cervix: Current Management and New Approaches: Review 3

Cancer of the Cervix: Current Management and New Approaches: Review 3

I have read with interest the paper entitled, "Cancer of the Cervix: Current Management and New Approaches," in this issue of ONCOLOGY. Shivnani et al have written a nice review of contemporary management of cervical cancer, focusing in large part on radiation therapy. Their consideration of evolving technologies and practice patterns give rise to a number of questions.

Chemotherapy Issues

Although chemotherapy has become standard therapy since 1999 for women with cervical cancer, its use and efficacy in both early and advanced disease remain in question. The five US trials discussed by Shivnani et al were diverse in terms of patient entry.[1-5] The study by Rose et al offered the only evidence of benefit of combined therapy in women with stage III or IVA cancer.[4,6] Morris et al found no survival benefit with chemoradiation for patients with stage III or IVA disease.[2] The only US trial to include stage IB/IIA disease treated with chemoradiation without surgery was Radiation Therapy Oncology Group (RTOG) 9001.[2] These patients had positive pelvic lymph nodes or tumors greater than 5 cm in diameter and appeared to benefit from the addition of chemotherapy. That said, we still need to question the role of chemotherapy with small-volume node-negative IB/IIA tumors.

Use of chemotherapy appears to increase survival but also toxicity. More focused selection criteria need to be determined to exclude patients who will not benefit. The doses of chemotherapy given with radiation are meant specifically to enhance the effect of radiation, rather than truly being systemic doses. If a patient has nonbulky pelvic disease, this may not be needed. In contrast, patients with bulky disease need chemotherapy both as a radiation sensitizer and as a systemic agent. The absence of systemic doses to address micrometastases may explain why there was no improvement in survival in stage III and IV disease in RTOG 9001.

 

Role of Imaging

In the five randomized cervical cancer studies that proved the efficacy of chemotherapy, eligible patients were required to have either surgical staging or a lymphangiogram to rule out occult para-aortic metastases. Unfortunately, off study, clinicians have been using computed tomography (CT) alone as proof or lack thereof of para-aortic disease. CT has a sensitivity of 34% and a specificity of 96%, whereas lymphangiography has a sensitivity of 79% and specificity of 73%.[7] Morris et al used lymphangiography or surgical staging to rule out para-aortic disease, but few institutions have the ability to perform and interpret these studies.[2] Surgical staging is probably the most rigorous method to rule out nodal disease if a sufficient number of nodes are submitted and sectioned properly.

Implementation of positron-emission tomography (PET) scanning prior to therapy may be the best imaging test for detecting para-aortic disease.[8-12] Grigsby et al have proven that the accuracy of PET in detecting subclinical para-aortic as well as supraclavicular disease was much greater than that of CT. With PET, we can identify patients with para-aortic disease and offer para-aortic irradiation rather than submitting them to upfront surgery and/or concurrent chemoradiation to the pelvis alone. For para-aortic positive patients, sequencing with chemotherapy remains important, as does dose escalation with intensity-modulated radiation therapy.[13-16] Future research will need to define a more effective paradigm for treating patients with para-aortic disease to improve survival—without excessive late toxicity. Radioprotection with agents such as amifostine (Ethyol) may also help.

 

Surgery vs Radiation

The choice of surgery vs radiation in early cervical cancer remains very physician-specific. Our surgical colleagues are not inclined to use imaging prior to pelvic exploration. Data on magnetic resonance imaging (MRI) demonstrates a much better ability to quantify tumor bulk and spread into the parametrium than physical examination alone.[17-20] PET can identify patients with occult lymph node disease, perhaps avoiding the delay of an aborted hysterectomy for these patients and allowing them to proceed with more appropriate chemoradiation.

Brachytherapy practice patterns are shifting in the United States. Cesium sources are becoming more difficult to buy due to decreased production. The Patterns of Care studies have shown that low-dose-rate (LDR) rather than high-dose-rate (HDR) brachytherapy has predominated in the US to date. The most recent (1996-1999) Patterns of Care study demonstrated that 27.8% of patients were treated with LDR, 13.3% with HDR, and 0.9% with a combination of LDR and HDR therapy. These statistics are similar to what was seen in the 1992-1994 survey.[21,22] Now that LDR options are decreasing, more radiation oncologists will need to consider either pulsed-dose-rate or HDR brachytherapy techniques. Despite the frequent use of this modality in Asia, India, and Europe, there is little consensus as to the optimum dose fractionation scheme. The Gynecologic Oncology Group and RTOG are now allowing HDR techniques for national protocols. There is hope that this will lead to a more in-depth analysis of outcome for HDR in the United States.

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