Physician's Weekly Article - Conference Highlights: The ASCO 2008 Annual Meeting

       The American Society of Clinical Oncology, or ASCO, held its 2008 annual meeting from May 30 to June 3 in Chicago. The features below highlight some of the news emerging from the meeting. For more information on these items and other research that was presented, go to www.asco.org/.

      Breast Cancer

      Slowing Cancer Growth in Newly Diagnosed Advanced Breast Cancer

      The Particulars: Previous studies have shown that adding bevacizumab to taxane chemotherapy agents for patients with metastatic breast cancer can improve progression-free survival. A phase III trial evaluated bevacizumab in combination with docetaxel for patients with newly diagnosed advanced breast cancer.

      Data Breakdown: At a median of 11 months follow up, patients receiving a higher dose of bevacizumab (15 mg/kg) plus docetaxel were 28% less likely to have their disease progress when compared with those receiving docetaxel only. Nearly two-thirds (63.1%) of recipients of higher-dose bevacizumab plus docetaxel had their tumors shrink, compared with a 55.2% rate for those receiving lower-dose (7.5 mg/kg) bevacizumab plus docetaxel and a 44.4% rate for patients receiving placebo plus docetaxel.

      Take Home Pearl: Adding bevacizumab to docetaxel chemotherapy appears to slow disease progression in patients without prior chemotherapy for locally advanced or metastatic breast cancer.

      Vitamin D Deficiency Linked to Poor Prognosis

      The Particulars: Vitamin D helps to regulate many aspects of cellular growth and differentiation. Previous studies have indicated that low vitamin D levels are associated with increased breast cancer risk.

      Data Breakdown: Women with vitamin D deficiency at the time of breast cancer diagnosis were 94% more likely to have their disease metastasize and 73% more likely to die when compared with women who had adequate vitamin D levels. More than one-third (37.5%) of breast cancer patients had vitamin D levels that were classified as “deficient” and another 38.5% were classified as having “insufficient” vitamin D levels. Only 24% of study group patients had adequate levels of vitamin D when they were diagnosed with cancer. Women deficient in vitamin D (less than 50 nmol/L) were more likely to have high-grade cancers.

      Take Home Pearl: Vitamin D deficiency appears to be common at breast cancer diagnosis and is associated with a poor prognosis.

      Advances & Quality of Life

      Improving Severe Cancer-Related Fatigue

      The Particulars: There are few ways to manage fatigue, one of the most common side effects of cancer and its treatment. Researchers set out to assess the effect of modafinil, a eugeroic agent that improves wakefulness, on treating severe cancer-related fatigue.

      Data Breakdown: In a randomized study, 320 cancer patients undergoing chemotherapy received modafinil; they were compared with 322 similar patients who received placebo. Patients who had the most severe fatigue at the beginning of the study demonstrated significant improvement from taking modafinil when compared with those in the placebo group. The medication group also had a significant beneficial effect on sleepiness.

      Take Home Pearl: Modafinil appears to be useful in the control of severe cancer-related fatigue, especially for patients with severe fatigue at baseline.

      Increasing Survival in Pancreatic Cancer

      The Particulars: Gemcitabine is the standard chemotherapy treatment for advanced pancreatic cancer that cannot be treated with surgery. A large, multicenter trial was performed to determine if it is beneficial to use gemcitabine earlier in the course of pancreatic cancer in patients who have undergone surgery for the disease.

      Data Breakdown: In the trial, 368 patients were randomized to receive postoperative gemcitabine or undergo observation, which included no specific anticancer treatment. All patients first had complete surgical removal of their tumor and had no remaining detectable macroscopic disease. Estimated disease-free survival at 3 and 5 years was 23.5% and 16.5%, respectively, for the gemcitabine group compared with 7.5% and 5.5% for the observation group. Overall survival at 3 and 5 years was 36.5% and 21.0%, respectively, for the gemcitabine group compared with 19.5% and 9.0% for the observation group.

      Take Home Pearl: Gemcitabine appears to more than double overall survival in patients who have undergone surgery for pancreatic cancer.

      Lung Cancer

      Combination Strategy Effective for NSCLC

      The Particulars: More than 80% of advanced non-small cell lung cancer (NSCLC) patients have tumors that express the EGFR gene. For patients with the most advanced NSCLC, 1-year survival is about 30% and 5-year survival is just 1% to 2%. Researchers evaluated the addition of cetuximab to platinum-based chemotherapy (cisplatin and vinorelbine) in a phase III study.

      Data Breakdown: NSCLC patients were randomized to receive either chemotherapy alone or platinum-based chemotherapy plus cetuximab. Overall survival was higher for those receiving cetuximab plus chemotherapy (11.3 months) than for patients receiving chemotherapy alone (10.1 months). Response rates were better in the chemotherapy plus cetuximab group (36.3%) than for those receiving chemotherapy alone (29.2%). Benefits with cetuximab were seen in patients with all histological subtypes of NSCLC.

      Take Home Pearl: Combining cetuximab with platinum-based chemotherapy appears to be effective as a first-line treatment for patients with advanced NSCLC, representing the first time that a targeted drug has shown a survival benefit.

      Assessing Maintenance Therapy in NSCLC

      The Particulars: Chemotherapy is a part of standard treatment for non-small cell lung cancer (NSCLC), but maintenance chemotherapy has not been previously proven to be of value. Progression-free and overall survival was assessed in patients whose cancer was stable following treatment with a platinum-containing drug. Patients were randomized to receive either pemetrexed, an FDA-approved agent for treating NSCLC that has progressed despite previous chemotherapy, or placebo.

      Data Breakdown: Progression-free survival was longer in the patients who received pemetrexed (4.3 months) than in those who received placebo (2.6 months). Overall survival was 13.0 months for the pemetrexed group and 10.2 months for the placebo group. The authors noted that results were preliminary and more data are necessary before conclusions can be drawn.

      Take Home Pearl: Maintenance therapy with pemetrexed given to patients 3 to 6 weeks after completing platinum-based “induction” chemotherapy appears to delay the time it takes for advanced NSCLC to progress by 50%.

      Colorectal Cancer

      The Impact of the KRAS Gene

      The Particulars: KRAS genetic mutations, which are found in 30% to 45% of all colorectal tumors, have previously been shown to predict whether patients will benefit from EGFR-inhibiting drugs as second-line therapy. Investigators evaluated patients who received chemotherapy alone with those who received chemotherapy plus cetuximab as part of initial therapy.

      Data Breakdown: Researchers sought to determine whether certain subsets of patients benefited more from the addition of cetuximab than others. Among patients with wild-type KRAS genes, 59.3% responded to treatment with chemotherapy and cetuximab, meaning their tumors shrank by more than half, compared with a 43.2% rate for patients who responded to chemotherapy alone. However, no difference in response rates was observed in patients with mutated KRAS genes in their tumors after receiving chemotherapy alone or after receiving chemotherapy and cetuximab.

      Take Home Pearl: Patients whose tumors contain the wild-type KRAS genes appear to be most likely to benefit from the addition of cetuximab to chemotherapy as part of first-line treatment of metastatic colorectal cancer when compared with patients who have a mutation in the KRAS genes.