Publications by authors named "Gregory D Leonard"

Although small cell carcinoma of the gastrointestinal (GI) tract is well-recognized, nonsmall cell type high-grade neuroendocrine carcinoma (HGNEC) of this site remains undefined. At the current time, neither the World Health Organization nor American Joint Committee on Cancer includes this condition in the histologic classifications, and consequently it is being diagnosed and treated inconsistently. In this study, we aimed at delineating the histologic and immunophenotypical spectrum of HGNECs of the GI tract with emphasis on histologic subtypes.

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Prostate cancer usually presents with early-stage disease, yet a significant proportion of patients present or will progress to androgen-independent, nonmetastatic prostate cancer (AIPC). Chemotherapy has demonstrated statistically significant improvements in palliation of AIPC. Docetaxel in particular has demonstrated high response rates as a single agent.

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International data from 2002 report 10.9 million new cases of cancer and 6.7 million cancer deaths.

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The treatment of metastatic colorectal cancer by chemotherapy alone was considered palliative and without the potential to cure patients unless patients were rendered resectable. We report two patients with metastatic colorectal cancer involving the liver who were considered inoperable and were treated with systemic chemotherapy using biomodulated 5-fluorouracil. Both patients received 5-fluorouracil and N-(phosphonoacetyl)-l-aspartic acid; one also received methotrexate, leucovorin, and triacetyluridine with the N-(phosphonoacetyl)-l-aspartic acid and 5-fluorouracil.

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In recent years, a number of phase III clinical trials have reported median survival times approaching 20 months using modern combination chemotherapy for metastatic colorectal cancer (CRC). Despite the advances in systemic therapy, this approach is still considered palliative because long-term survival or cure is extremely rare. Surgery or the use of ablative techniques may result in prolonged survival for patients with liver metastases, but only a minority of cases are suitable for local therapy.

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Background: New chemotherapy regimens for patients with colorectal cancer have improved survival, but at the cost of clinical toxicity. Oxaliplatin, an agent used in first-line therapy for metastatic colorectal cancer, causes acute and chronic neurotoxicity. This study was performed to carefully assess the incidence, type and duration of oxaliplatin neurotoxicity.

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Purpose: In preclinical studies, sequential exposure to irinotecan (CPT-11) then fluorouracil (5-FU) is superior to concurrent exposure or the reverse sequence; a 24-hour infusion of CPT-11 may be better tolerated than shorter infusions.

Experimental Design: CPT-11 was first given at four levels (70-140 mg/m(2)/24 hours), followed by leucovorin 500 mg/m(2)/0.5 hours and 5-FU 2,000 mg/m(2)/48 hours on days 1 and 15 of a 4-week cycle.

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Colorectal carcinoma is one of the most common cancers in the world, and more than 50% of these patients develop liver metastases. Despite recent advances, systemic chemotherapy for metastatic disease without the use of surgery is considered palliative, as there are rarely long-term survivors. However, patients who are candidates for surgical resection of their liver metastases can have a prolonged survival or possibly a cure.

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Biliary tract cancer, which consists of gall bladder cancer and cholangio-carcinoma, presents many challenges to practising physicians. It is a relatively rare cancer that often causes a diagnostic dilemma, as its presentation may be similar to that of non-malignant conditions. In many cases, histological or cytological confirmation of a cancer diagnosis is not possible preoperatively.

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Job's or hyper immunoglobulin E recurrent infection syndrome (Hyper-IgE syndrome) is a rare, often inherited multisystem disorder, characterized by cutaneous abscesses, pneumonia, elevated IgE levels and skeletal defects. We report a case of a 22-year-old man with Job's syndrome who presented with back pain. He was found to have diffuse large B-cell lymphoma involving his second lumbar vertebrae and spleen.

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Oxaliplatin-based combination chemotherapy is an option for first-line therapy of metastatic colorectal cancer. It is associated with acute hyperexcitability of motor and sensory nerves, and a cumulative sensory axonal neuropathy. We describe a 56-year-old male with metastatic colorectal cancer treated with oxaliplatin and capecitabine who developed a rapidly ascending motor and sensory neuropathy, which rendered him wheelchair-bound.

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The incidence of ductal carcinoma in situ (DCIS), a noninvasive form of breast cancer, has increased markedly in recent decades, and DCIS now accounts for approximately 20% of breast cancers diagnosed by mammography. Laboratory and patient data suggest that DCIS is a precursor lesion for invasive cancer. The appropriate classification of DCIS has provoked much debate; a number of classification systems have been developed, but there is a lack of uniformity in the diagnosis and prognostication of this disease.

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A 69-year-old postmenopausal woman with newly diagnosed inflammatory breast cancer was evaluated for a pelvic mass found incidentally during staging computed tomography (CT) scans. Her serum cancer antigen (CA) 125 was greater than 900 U/ml, but laparoscopic examination of the ovaries was normal. Her breast cancer was deemed metastatic by virtue of a supraclavicular lymph node, but she had no visceral or bone metastasis.

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Drug resistance remains one of the primary causes of suboptimal outcomes in cancer therapy. ATP-binding cassette (ABC) transporters are a family of transporter proteins that contribute to drug resistance via ATP-dependent drug efflux pumps. P-glycoprotein (P-gp), encoded by the MDR1 gene, is an ABC transporter normally involved in the excretion of toxins from cells.

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Oesophageal carcinoma is one of the commonest cancers in the world and has an increasing incidence in Western civilisation. As the epidemiology of the disease has changed so too has our treatment strategies. The present standard of care is surgery but this is associated with disappointing survival figures.

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P-glycoprotein (P-gp), a plasma membrane pump associated with multidrug resistance (MDR), is a member of the superfamily of ATP-binding cassette (ABC) transporters. The discovery that inhibitors of drug efflux can increase drug accumulation and reverse drug resistance in the laboratory has led to the clinical development of a number of P-gp inhibitors. Initial studies were performed with agents already in use in the clinic for other indications, the 'first generation' studies.

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