Chemotherapy

Potential benefit of improved local tumor control in patients with prostate carcinoma

BACKGROUND

In the case of prostate carcinoma, radiation therapy is a locally applied treatment modality in a malignancy known for systemic dissemination. Because significant efforts and resources currently are being consumed to improve local tumor control, failure patterns and potential curative gain deserve appropriate assessment.

METHODS

From 1975-1989, 647 patients with clinically localized prostate carcinoma were definitively irradiated for biopsy-proven adenocarcinoma of the prostate. Failure patterns were examined, and survival advantage based on improvement in either local or distant disease control was calculated. Distant metastatic rate and cause-specific survival analyses were used as parameters by which to compare the outcome for patients in whom local tumor control was achieved with patients who experienced local failure, thereby assessing further the importance of the effectiveness of locally applied therapy.

RESULTS

Three hundred ninety-two (61%) patients at the time of this writing were clinically disease free. Sixty-two (10%) patients failed locally only, 133 (20%) distantly only, and 60 (9%) developed local and distant recurrent disease. Both local and distant failure rates were higher in patients with more advanced stage lesions at presentation, and distant failure rates significantly increased in patients with less differentiated tumors. Pretreatment prostate-specific antigen was found to be useful in predicting recurrence patterns. Overall, there appeared to be more potential for improvement in survival secondary to reducing distant metastasis. The distant survival advantage (DSA) of reducing distant metastases, compared with the local survival advantage (LSA) of improving local tumor control, was 26 versus 14%. Although DSA was greater than LSA within each stage category, the potential to improve survival was most significant in the Stage C group, where DSA was 35% and LSA 16%. Although LSA varied little according to tumor grade, DSA was dependent on tumor grade and varied from 13% for well differentiated lesions to 38% for poorly differentiated lesions. Distant failure free survival at 10 years was 63% for patients with local control and 45% for those with local failure (P = 0.01). Similarly, 10-year cause-specific survival was 75% in locally controlled patients compared with 48% for those with local recurrence (P < 0.001).

CONCLUSIONS

Although better local tumor control should translate into at least modest survival gain for patients with prostate carcinoma, additional advantage may be seen with improved systemic therapy or perhaps earlier diagnosis to reduce further the distant metastasis rate.

Tumor metastasis: current biologic concepts and their implications for control of residual disease

Metastatic disease presents an important obstacle to curative cancer therapy. This article reviews cancer biology concepts relevant to the pathogenesis of tumor metastasis and their implications for the surgical oncologist seeking to control or eradicate metastatic disease.

Platinum drug delivery and radiation for locally advanced prostate cancer

Combined therapies of cisplatin and radiation have resulted in clinical reports of apparent efficacious control of locoregional cancer and enhanced survival. Mechanisms of interaction between platinum and radiation that may explain these clinical observations all have in common the prediction that higher concentrations of platinum in all tumor cells close in time to irradiation should lead to greater potentiation of radiation-induced killing of those cells. Cisplatin is thus viewed as providing some radiation-equivalent, or a radiation dose-effect factor, for sterilization of tumors. One disease site that has not been well investigated for response to cisplatin plus radiation therapy, but that could benefit from it, is locally advanced prostate cancer. A body of literature now supports the view that local control of stage C (T3, N0, M0) prostate cancer is correlated with disease-free survival. This correlation makes prostate cancer a candidate for potentially achieving improved cure rates following local tumor sterilization by combining cisplatin with radiation therapy. The need and approaches to optimize delivery of cisplatin within tumor tissue is explored. Increasing cisplatin concentration to all the cells of a tumor, i.e., homogeneously delivering systemic high-dose cisplatin, should benefit the efficacious response otherwise expected for cisplatin combined with radiation. Strategies to increase the homogeneity of cisplatin delivery to a tumor are considered to be those that increase perfusion to that tumor. Vasoactive agents used in anticancer protocols are especially considered for their potential value in serving to increase tumor perfusion. These protocol-inclusive agents include certain cytokines and L-arginine antagonists, and should be better managed and accepted in practice compared to other vasoactive agents that need to be developed as specific additives to protocol designs.

TRH: mediator of prolactin in the prostate?

Thanks to our preoccupation with androgen ablative therapy, no significant progress has been made in combating prostate cancer (PCa) in 50 years. Also, there have been only limited advances in medical treatment of benign prostatic hyperplasia (BPH). The intent of this essay is to explore the mode of participation of prolactin (Prl) in prostatic physiology in the hope that such knowledge will reveal new avenues through which both BPH and PCa can be opposed-even prevented. An especially novel aspect of this study is the recognition of the presence and androgen- and prolactin-dependent concentration of the tripeptide, thyrotropin-releasing hormone (TRH) in prostatic tissue. It is hypothesized that, whereas TRH is the hypothalamic stimulus of hypophyseal Prl secretion, it may, in the prostate, serve as the mediator of Prl's independent and androgen-dependent controls of the gland's growth and function. Through an overview of these relationships, methods are suggested both for their study and for their adaptation to early detection and prevention of imminent pathogenesis.

Vocal cord paralysis from prostatic carcinoma metastasizing to the larynx

According to 1992 Cancer Statistics, prostate carcinoma is once again predicted to be the most common cancer in men, exceeding the incidence of lung cancer. In American men, this cancer is estimated to be the second most frequent cause of cancer deaths by site. Although metastases have been reported in practically every organ in the body, prostatic cancer most often metastasizes to bones, regional lymph nodes, and viscera. Although secondary involvement of the larynx by malignant neoplasms arising in contiguous structures is well known, metastatic cancer to the larynx from a prostate carcinoma is rare. This report discusses a unique case that presented with hoarseness resulting from vocal cord paralysis. The diagnosis of the tumor was confirmed by immunoperoxidase stains for prostate-specific antigen.

Methotrexate and estramustine phosphate in the treatment of hormone-refractory prostatic carcinoma. Preliminary study

The authors report preliminary results of a study performed on six patients with by advanced, hormone-refractory prostate cancer. These patients were treated by estramustine phosphate (10 mg/kg) and methotrexate (60 mg/mq). Low toxicity allows the use of this therapy in outpatient regimens. Moreover, the high rate of partial responses (five patients) shows the remarkable efficacy of this therapy, even if follow-up and number of patients are not sufficient to reach definitive conclusions.