Hilliard F. Seigler

Mutations of the BRAF gene in human cancer

Cancers arise owing to the accumulation of mutations in critical genes that alter normal programmes of cell proliferation, differentiation and death. As the first stage of a systematic genome-wide screen for these genes, we have prioritized for analysis signalling pathways in which at least one gene is mutated in human cancer. The RAS–RAF–MEK–ERK–MAP kinase pathway mediates cellular responses to growth signals. RAS is mutated to an oncogenic form in about 15% of human cancer. The three RAF genes code for cytoplasmic serine/threonine kinases that are regulated by binding RAS. Here we report BRAF somatic missense mutations in 66% of malignant melanomas and at lower frequency in a wide range of human cancers. All mutations are within the kinase domain, with a single substitution (V599E) accounting for 80%. Mutated BRAF proteins have elevated kinase activity and are transforming in NIH3T3 cells. Furthermore, RAS function is not required for the growth of cancer cell lines with the V599E mutation. As BRAF is a serine/threonine kinase that is commonly activated by somatic point mutation in human cancer, it may provide new therapeutic opportunities in malignant melanoma.

The orderly progression of melanoma nodal metastases

ObjectiveThe aim of this study was to determine the order of melanoma nodal metastases. Summary Background DataMost solid tumors are thought to demonstrate a random nodal metastatic pattern. The incidence of skip nodal metastases precluded the use of sampling procedures of first station nodal basins to achieve adequate pathological staging. Malignant melanoma may be different from other malignancies in that the cutaneous lymphatic flow is better defined and can be mapped accurately. The concept of an orderly progression of nodal metastases is radically different than what is thought to occur in the natural history of metastases from most other solid malignancies. MethodsThe investigators performed preoperative and intraoperative mapping of the cutaneous lymphatics from the primary melanoma in an attempt to identify the “sentinel” lymph node in the regional basin. All patients had primary melanomas with tumor thicknesses > 0.76 mm and were considered candidates for elective lymph node dissection. The sentinel lymph node was defined as the first node in the basin from which the primary site drained. The sentinel lymph node was harvested and submitted separately to pathology, followed by a complete node dissection. The null hypothesis tested was whether nodal metastases from malignant melanoma occurred in equal proportions among sentinel and nonsentinel nodes. ResultsForty-two patients met the criteria of the protocol based on prognostic factors of their primary melanoma. Thirty-four patients had histologically negative sentinel nodes, with the rest of the nodes in the basin also being negative. Thus, there were no skip metastases documented. Eight patients had positive sentinel nodes, with seven of the eight having the sentinel node as the only site of disease. In these seven patients, the frequency of sentinel nodal metastases was 92%, whereas none of the higher nodes had documented metastatic disease. Nodal involvement was compared between the sentinel and nonsentinel nodal groups, based on the binomial distribution. Under the null hypothesis of equality in distribution of nodal metastases, the probability that all seven unpaired observations would demonstrate that involvement of the sentinel node is 0.008.

Preoperative radiation and chemotherapy in the treatment of adenocarcinoma of the rectum

ObjectiveIn this study, the impact of preoperative chemotherapy and radiation on the histopathology of a subgroup of patients with rectal adenocarcinoma was examined. As well, survival, disease-free survival and pelvic recurrence rates were examined, and compared with a concurrent control group. Summary Background DataThe optimal treatment of large rectal carcinomas remains controversial; current therapy usually involves abdominoperineal resection plus postoperative chemoradiation; the combination can be associated with significant postoperative morbidity. In spite of these measures, local recurrences and distant metastases continue as serious problems. MethodsFluorouracil, cisplatin, and 4500 cGy were administered preoperatively over a 5-week period, before definitive surgical resection in 43 patients. In this group of patients, all 43 had biopsyproven lesions >3 cm (median diameter), involving the entire rectal wall (as determined by sigmoidoscopy and computed tomography scan), with no evidence of extrapelvic disease. The patients ranged from 31 to 81 years of age (median 61 years), with a male:female ratio of 3:1. A concurrent control group consisting of 56 patients (median: 62 years, male:female ration of 3:2) with T2 and T3 lesions was used to compare survival, disease-free survival, and pelvic recurrence rates. ResultsThe preoperative chemoradiation therapy was well tolerated, with no major complications. All patients underwent repeat sigmoidoscopy before surgery; none of the lesions progressed while patients underwent therapy, and 22 (51%) were determined to have complete clinical response. At the time of resection, 21 patients (49%) had gross disease, 9 (22%) patients had only residual microscopic disease, and 11 (27%) had sterile specimens. Of the 30 patients with evidence of residual disease, 4 had positive lymph nodes. In follow-up, 39 of the 43 remain alive (median follow-up = 25 months), and only 1 of the 11 patients with complete histologic response developed recurrent disease. Six of the 32 patients with residual disease (2 with positive nodes) have developed metastatic disease in follow-up (median time to diagnosis 10 months, range 3–15 months). Three of these patients with metastases have died (median survival after diagnosis of

Lethal “Thin” Malignant Melanoma: Identifying Patients at Risk

Thin melanomas can metastasize and be lethal. The purpose of this review was to identify negative risk factors in patients with melanomas less than 0.76 mm thick. Six hundred and eighty-one (681) such patients are reviewed in this study. Of those referred without metastatic disease (583 patients), metastases developed in 4.8% after a mean followup of 3.6 years. Of those referred with metastatic disease (98 patients), mortality was 35% after a mean followup of 5.9 years. Male patients (p < 0.04) and patients with axial primaries (p < 0.05) were at an increased risk of metastasis. Severe histologie regression was present in 40% of the primary lesions that metastasized and in only 17% of similar lesions that did not (p < 0.001). Increased age was associated with increased local skin metastases, but not with increased nodal or distant metastases. A prognostic model was designed, using two clinical risk factors (axial primary site and male sex) and two histologie risk factors (Clarks Level IV and severe histologie regression). The prognostic model identified a low-risk population—women with extremity primaries—with an actuarial risk of metastasis at 10 years that was less than 3%. Patients with either (1) both clinical risk factors or (2) one clinical risk factor and one histologie risk factor were identified as high-risk patients. Their actuarial risk of metastasis was 11% at 5 years and 22% at 10 years (p = 0.0084). Identifying high-risk and low-risk patients with thin melanomas may improve guidelines for the application of adjuvant therapies to this population.

Surgical management of regional lymph nodes in patients with melanoma. Experience with 4682 patients.

Summary Background DataLarge retrospective studies suggest that ELND may improve the prognosis of patients with intermediate-thickness melanomas; however, that improvement has not been observed in two randomized prospective controlled trials.MethodsThe charts of 4682 patients treated at a single ins

Late recurrence of malignant melanoma. Analysis of 168 patients.

Analysis of 7104 patients with melanoma seen at Duke University identified 168 who experienced their first recurrence 10 or more years after diagnosis, for an incidence of 2.4%. This included patients with all stages of disease. There was no sex, age, or primary site predominance. The mean disease-free interval for cutaneous melanomas was 14.3 years versus 22.3 years for ocular primary melanomas. The prognosis following relapse was related to the site of recurrence. Survival after local or regional node recurrence was often prolonged; survival after distant metastases was usually limited. Patients with ocular primaries had the highest incidence of distant metastases, and the shortest subsequent survival. An additional 483 patients were identified who survived 10 or more years without evidence of recurrence; of these 651 patients with long disease-free intervals, 25% (168 of 651) developed recurrent disease. This demonstrates that a 10-year disease-free interval cannot be considered a cure, and emphasizes the importance of continued annual follow-up.

Neoadjuvant chemoradiation for rectal cancer: analysis of clinical outcomes from a 13-year institutional experience.

ObjectiveTo examine clinical outcomes in patients receiving neoadjuvant chemoradiation for locally advanced rectal adenocarcinoma. Summary Background DataPreoperative radiation therapy, either alone or in combination with 5-fluorouracil-based chemotherapy, has proven both safe and effective in the treatment of rectal cancer. However, data are lacking regarding which subgroups of patients benefit from the therapy in terms of decreased local recurrence and increased survival rates. MethodsA retrospective chart review was performed on 141 consecutive patients who received neoadjuvant chemoradiation (5-fluorouracil ± cisplatin and 4,500–5,040 cGy) for biopsy-proven locally advanced adenocarcinoma of the rectum. Surgery was performed 4 to 8 weeks after completion of chemoradiation. Standard statistical methods were used to analyze recurrence and survival. ResultsMedian follow-up was 27 months, and mean age was 59 years (range 28–81). Mean tumor distance from the anal verge was 6 cm (range 1–15). Of those staged before surgery with endorectal ultrasound or magnetic resonance imaging, 57% of stage II patients and 82% of stage III patients were downstaged. The chemotherapeutic regimens were well tolerated, and resections were performed on 140 patients. The percentage of sphincter-sparing procedures increased from 20% before 1996 to 76% after 1996. On pathologic analysis, 24% of specimens were T0. However, postoperative pathologic T stage had no effect on either recurrence or survival. Positive lymph node status predicted increased local recurrence and decreased survival. ConclusionsNeoadjuvant chemoradiation is safe, effective, and well tolerated. Postoperative lymph node status is the only independent predictor of recurrence and survival.

Complete response to neoadjuvant chemoradiation for rectal cancer does not influence survival

Background: Up to 30% of patients with locally advanced rectal cancer have a complete clinical or pathologic response to neoadjuvant chemoradiation. This study analyzes complete clinical and pathologic responders among a large group of rectal cancer patients treated with neoadjuvant chemoradiation.Methods: From 1987 to 2000, 141 consecutive patients with biopsy-proven, locally advanced rectal cancer were treated with preoperative 5-fluorouracil-based chemotherapy and radiation. Clinical restaging after treatment consisted of proctoscopic examination and often computed tomography scan. One hundred forty patients then underwent operative resection, with results tracked in a database. Standard statistical methods were used to examine the outcomes of those patients with complete clinical or pathologic responses.Results: No demographic differences were detected between either clinical complete and clinical partial responders or pathologic complete and pathologic partial responders. The positive predictive value of clinical restaging was 60%, and accuracy was 82%. By use of the Kaplan-Meier life table analysis, clinical complete responders had no advantage in local recurrence, disease-free survival, or overall survival rates when compared with clinical partial responders. Pathologic complete responders also had no recurrence or survival advantage when compared with pathologic partial responders. Of the 34 pathologic T0 tumors, 4 (13%) had lymph node metastases.Conclusions: Clinical assessment of complete response to neoadjuvant chemoradiation is unreliable. Micrometastatic disease persists in a proportion of patients despite pathologic complete response. Observation or local excision for patients thought to be complete responders should be undertaken with caution.

Malignant melanoma arising during pregnancy. A study of 100 patients.

Melanoma is often diagnosed in young adults, a significant proportion of whom are women of child-bearing age. The prognosis of women diagnosed with melanoma during a pregnancy continues to be debated. One hundred patients, ages 19 to 40 years, have been identified who were pregnant at the time of diagnosis of their melanoma. All were treated with local excision. Sixteen per cent underwent elective lymph node dissections. Immunotherapy was administered to 83% of patients. Mean follow-up was 6.8 years from the date of diagnosis. The patients were compared to an age-matched group of 86 women who were not pregnant at the time of diagnosis. Overall mortality during the follow-up period was 25% in the pregnant group and 23% in the control group. Among the pregnant group, there was an increased incidence of lymph node metastases during the follow-up period (39% versus 26%, p = 0.053). Among stage I patients, there was a significantly shorter DFI for the pregnant group (p = 0.039), with 50% of pregnant patients and 67% of control patients free of disease at 10 years. Similarly, among stage 1 patients, the time to development of lymph node metastases was shorter in the pregnant group (p = 0.021). Multivariate analysis demonstrated that pregnancy at diagnosis was significantly associated with the development of metastatic disease (p = 0.008), when controlling for tumor site, thickness, and Clark level. Patients who developed melanoma during pregnancy did not, however, have a significant decrease in survival.

Long-term survival in 2,505 patients with melanoma with regional lymph node metastasis

ObjectiveTo examine the long-term outcomes of patients with melanoma metastatic to regional lymph nodes. Summary Background DataRegional lymph node metastasis is a major determinant of outcome for patients with melanoma, and the presence of regional lymph node metastasis has been commonly used as an indication for systemic, often intensive, adjuvant therapy. However, the risk of recurrence varies greatly within this heterogeneous group of patients. MethodsDatabase review identified 2,505 patients, referred to the Duke University Melanoma Clinic between 1970 and 1998, with histologic confirmation of regional lymph node metastasis before clinical evidence of distant metastasis and with documentation of full lymph node dissection. Recurrence and survival after lymph node dissection were analyzed. ResultsEstimated overall survival rates at 5, 10, 15, and 20 years were 43%, 35%, 28%, and 23%, respectively. This population included 792 actual 5-year survivors, 350 10-year survivors, and 137 15-year survivors. The number of positive lymph nodes was the most powerful predictor of both overall survival and recurrence-free survival; 5-year overall survival rates ranged from 53% for one positive node to 25% for greater than four nodes. Primary tumor ulceration and thickness were also powerful predictors of both overall and recurrence-free survival in multivariate analyses. The most common site of first recurrence after lymph node dissection was distant (44% of all patients). ConclusionsPatients with regional lymph node metastasis can enjoy significant long-term survival after lymph node dissection. Therefore, aggressive surgical therapy of regional lymph node metastases is warranted, and each individual’s risk of recurrence should be weighed against the potential risks of adjuvant therapy.