Epidermal growth factor (EGF) activates nuclear factor-kappaB through IkappaBalpha kinase-independent but EGF receptor-kinase dependent tyrosine 42 ph

Overexpression of epidermal growth factor (EGF) receptor and constitutive activation of nuclear factor-B (NF-B) are frequently encountered in tumor cells. Although EGF has been shown to induce NF-B activation, the mechanism is poorly understood. EGF activated NF-B DNA binding, induced NF-B reporter activity and the expression of antiapoptotic and cell-proliferative gene products. Interestingly, non-small cell lung adenocarcinoma cell lines (HCC827 and H3255), which exhibit EGFR amplification, showed ligand-independent activation of NF-B. Unlike tumor-necrosis factor (TNF), however, EGF failed to induce IB phosphorylation and ubiquitination and the activation of IB kinase (IKK). Although DN-IKK inhibited TNF-induced NF-B activity, DN-IKK had no effect on EGF-induced NF-B activation, suggesting that EGF-induced NF-B activation is IKK independent. Using dominant-negative plasmids, we also demonstrated the role of TRADD, TRAF2, NIK and Ras in EGF-induced NF-B activation. By using specific antibodies and IB plasmid, which is mutated at tyrosine 42 to phenylalanine, we show that EGF induced the tyrosine phosphorylation of IB at residue 42. Furthermore, EGF receptor kinase inhibitor blocked IB phosphorylation and consequent NF-B activation. Overall, our results indicate that tyrosine phosphorylation of IB at residue 42 is critical for EGF-induced NF-B activation pathway.

Activity of endovesical gemcitabine in BCG-refractory bladder cancer patients: a translational study

Intravesical gemcitabine (Gem) has shown promising activity against transitional cell carcinomas (TCC) of the bladder, with moderate urinary toxicity and low systemic absorption. The present phase II study evaluated the activity of biweekly intravesical treatment with Gem using a scheme directly derived from in vitro preclinical studies. Patients with Bacille Calmette-Guérin (BCG) -refractory Ta G3, T1 G1-3 TCC underwent transurethral bladder resection and then intravesical instillation with 2000 mg Gem diluted in 50 ml saline solution on days 1 and 3 for 6 consecutive weeks. Thirty-eight (95%) of the 40 patients showed persistent negative post-treatment cystoscopy and cytology 6 months after Gem treatment, while the remaining 2 patients relapsed at 5 and 6 months. At a median follow-up of 28 months, recurrences had occurred in 14 patients. Among these, four had downstaged (T) disease, three had a lower grade (G) lesion and three had a reduction in both T and G. Urinary and systemic toxicity was very low, with no alterations in biochemical profiles. In conclusion, biweekly instillation of Gem proved active in BCG-refractory Ta G3, T1 G1-3 TCC. Our results highlight the importance of preclinical studies using in vitro systems that adequately reproduce the conditions of intravesical clinical treatment to define the best therapeutic schedule.

Androgen withdrawal improves tumor hypoxia in prostate cancer

Around one-quarter of patients who receive radical treatment for prostate cancer subsequently develop progressive disease. The mechanisms underlying this malignant progression are, however, poorly elucidated. Recently, Milosevic and co-workers have investigated the effects of androgen withdrawal on prostate cancer hypoxia. Androgen withdrawal is known to result in tumor regression in the majority of patients, and is effective in combination with radiotherapy.

Genetic cooperation between p21Cip1 and INK4 inhibitors in cellular senescence and tumor suppression

Cell-cycle inhibitors of the Cip/Kip and INK4 families are involved in cellular senescence and tumor suppression. Some of these proteins, p21^Cip1, p16^INK4a and p15^INK4b, are coexpressed in response to antiproliferative signals such as cellular senescence resulting in cell-cycle arrest. To understand the roles of these inhibitors and their synergistic effect, we have characterized the growth properties and senescent behavior of primary cells deficient in p21^Cip1 and expressing an endogenous Cdk4^R24C (cyclin-dependent kinase) mutant (Cdk4^R24C knock-in cells) insensitive to INK4 proteins. Inactivation of both p21^Cip1 and INK4 pathways strongly cooperate in suppressing cellular senescence in vitro. These double mutant cells behavior as immortal cultures and display high sensitivity to cellular transformation by oncogenes. Moreover, mice double mutant in the INK4 and p21^Cip1 pathways (Cdk4^R24C; p21^Cip1-null mice) display an increased incidence of specific sarcomas, suggesting a significant cooperation between these two families of cell-cycle inhibitors in senescence responses and tumor suppression in vivo.

Postulate 5: the psychological burden of untreated cancer

The psychological burden of living with untreated cancer has less impact on the quality of life than unnecessary, but curative, therapy. The psychological effects of living for many years with untreated cancer are unknown; however, the evidence indicates it is the diagnosis of cancer that takes a psychological toll, whether patients are treated curatively or not. A companion study to the randomized trial of surgery versus watchful waiting in Sweden described above found no significant psychological difference at 5 years between the two study arms. The occurrence of worry, anxiety or depression was equal between the treatment and the observation arms. Surveillance is clearly stressful for some men; however, concern about PSA recurrence is common among both treated and untreated patients. Patients who are educated to appreciate the indolent natural history of most good-risk prostate cancers might avoid much of this anxiety. Further quality-of-life studies focusing on this issue are clearly warranted.

Postulate 4: patient-risk reclassification

Choo et al. and Klotz et al. were the first groups to use a prospective active-surveillance protocol that incorporated a selective, delayed intervention for the patient subset with rapid PSA or grade progression on repeat biopsy. The eligibility criteria included patients with stage T1c or T2a prostate cancer who had a Gleason score of 6 or less and a PSA level of 10 ng/ml or less. For patients over 70 years of age, these criteria were relaxed to include a Gleason score of 7 (3 + 4) or less and/or a PSA value of 15 ng/ml or less. The cohort of active-surveillance patients comprised 299 patientsThe median age was 70 years (range 49–84 years); 80% of patients had a Gleason score of 6 or less, and the same proportion had a PSA level greater than 10 ng/ml (median 6.5 ng/ml). The median follow-up period was 72 months, during which time 101 (34%) patients came off active surveillance, whereas 198 patients remained on active surveillance. Of patients discontinuing surveillance, the reason was rapid biochemical progression in 15%, clinical progression in 3%, histologic progression in 4%, and patient preference in 12%. There was no correlation between grade progression and PSA doubling time. At a median follow-up of 7 years (range 2–11 years), the overall survival was 85% and disease-specific survival was 99%.

Only 3 out of 299 patients had died of prostate cancer at the time of writing this review. All three patients had PSA doubling times of greater than 2 years, and death occurred 3.0, 5.1 and 5.2 years after diagnosis. All three patients exhibited the same pattern of clinical progression: initial favorable prognostic factors; a rapid rise in PSA level, which led to treatment at 6, 9 and 11 months, respectively, after the initial diagnosis; and a further progressive rise in PSA level and clinically apparent bone metastases within 1 year of treatment, leading to androgen-deprivation therapy. All three patients died within 3 years of the initiation of hormone therapy. This very rapid progression after diagnosis indicates that these patients had occult metastases at the time of initial disease presentation and their outcome would not have been altered by earlier treatment. In the Swedish trial, there was almost no difference between the two groups before 5 years had elapsed.

In the Choo et al. study, the median PSA doubling time, calculated by logarithmic regression, was 7 years In total, 22% of patients had a PSA doubling time of greater than 3 years, whereas 42% had a PSA doubling time of over 10 years, which indicates an indolent course of disease in these patients. The Gleason score remained stable in 92% of patients; only 8% of patients demonstrated a marked rise in their Gleason score, classed as an increase of at least two points. In this group, 29 patients (10% of the cohort) had a radical prostatectomy as a result of a short PSA doubling time or tumor-grade progression. All these patients had an initial Gleason score of 5 or 6, a PSA value greater than 10 ng/ml and a tumor stage of pT1–2 at study entry. The final pathology was stage pT2 in 18 patients, stage pT3a in 11 patients, stage T3c in 1 patient and node-positive in 1 patient. Of the 18 patients with a PSA doubling time of greater than 3 years, only 7 patients had positive margins. This result suggests that even among the worst subset of the cohort, that is to say those reclassified as higher risk over time, the majority could be cured by delayed therapy.

Postulate 3: adverse effects and cost considerations

No treatment is minimal in terms of adverse effects and cost. All widely accepted, local, definitive treatments for prostate cancer, including surgery, brachytherapy, external-beam irradiation and cryosurgery, induced erectile dysfunction in a considerable proportion of patients, and these treatments were associated with serious adverse effects in several patients.

Postulate 2: patient selection for surveillance

The patients who fall into the active-surveillance category can be identified with reasonable accuracy. The 'gold standard' for clinically insignificant prostate cancer, used by virtually all clinicians who attempt to predict minimal disease according to clinical parameters, is a radical prostatectomy specimen containing less than 0.5 ml of prostate cancer with a Gleason score of 6 or less. Stamey et al. devised this reference standard after examination of prostate glands obtained from 139 consecutively sampled radical cystoprostatectomy specimens, of which 55 (40%) had incidental prostate cancer. The authors concluded that only tumor volumes above the 92^nd percentile (0.5–6.1 ml) were clinically significant, according to the assumption that the clinically significant cancer rate and clinical prevalence were both 8%. This approach is arbitrary and concerning.

Many groups have reported the incidence of insignificant disease using this definition. The incidence varies from 30% in patients with stage T1c disease, as reported by Epstein et al.,to values as low as 9–12%.The clinical criteria for predicting minimal disease include a Gleason score of 6 or less, a low PSA density of <0.15,>

Postulate 1: detection through screening

Prostate-cancer screening results in the detection of disease that in many patients is not clinically significant. Screening for prostate cancer on the basis of prostate biopsy for men with elevated levels of serum PSA or an abnormal digital rectal examination results in many men whose lives are not at threat from prostate cancer being diagnosed with the disease. In the US, there are 2.74 million men who are aged 50–70 years and have a PSA level greater than 2.5 ng/ml. Catalona's group advocates using a PSA cut-off point of 2.5 ng/ml for biopsy in men aged 50 years or older. If all American men in this age-group with a PSA level greater than 2.5 ng/ml were subjected to a biopsy, 775,000 cases of prostate cancer would be diagnosed this year in the US alone. This is 543,000 more cases than the 232,000 diagnosed in 2005, and 25 times the 30,350 men expected to die of prostate cancer each year in the US. PSA screening has resulted in a progressive decrease in the extent of cancer present at the time of diagnosis (i.e. stage migration). As a consequence, the proportion of patients newly diagnosed with prostate cancer who fall into the 'favorable-risk' category has increased and now constitutes almost half of patients with the disease.

The aggressiveness of cancer can be predicted by the use of existing clinical parameters. The parameters most widely used are the tumor grade or Gleason score, PSA level, and tumor stage. Favorable-risk prostate cancer is characterized by a Gleason score of 6 or less, a PSA level of 10 ng/ml or less, and stage T1c–T2a disease Importantly, although patients with these characteristics have a much more favorable natural history and progression rate than those who have a higher Gleason grade or PSA level, in a few patients tumors will still progress to advanced, incurable prostate cancer and death.

Autopsy studies have demonstrated that prostate cancer typically begins in the third or fourth decade of life In most patients, this means that there is a period of slow subclinical tumor progression from a microscopic focus of disease, which lasts approximately 30 years, followed by a period of clinical progression (potentially, but not invariably, leading to metastatic disease and death), which lasts about 15 years. The implication is that most patients have a long window of curability. This is particularly true for patients with favorable-risk, low-volume disease.

Data on a large group of patients in Connecticut, US assessed by watchful waiting have been reported at 20 years. These data confirm the powerful predictive value of the Gleason score. In the pre-PSA screening cohort, 23% of untreated patients with a Gleason score of 6 died of prostate cancer within 20 years. Of the patients with a Gleason score of 7, about 65% died of prostate cancer within 20 years. In addition, the authors recently reanalyzed prostate pathology slides that were initially read between 1990 and 1992, using contemporary Gleason scoring. The study demonstrated clearly that there has been a shift in grade interpretation during the past 15 years. This shift is largely the result of the removal of Gleason scores 2–4 from the classification, the inclusion of small proportions of high-grade cancer into the grading system, and the reclassification of cribriform-pattern cancer from a Gleason score of 3 to a Gleason score of 4. Many cancers diagnosed 20 years ago as a Gleason score of 6 would be classified as a Gleason score of 7 today. The Connecticut study results probably represent a 'worst case' scenario for the expected mortality from untreated cancer with a Gleason score of 6. This means that the mortality from untreated, non-screen-detected prostate cancer in patients with contemporary Gleason scores of 6 might be as low as 10% at 20 years.

Why would any healthy person, newly diagnosed with cancer, elect not to have curative treatment? This reasonable question is often posed by patients who have newly diagnosed prostate cancer and are presented with the option of active surveillance. Communicating the answer to this question clearly is a crucial component of the active-surveillance strategy. The basis for this approach, the principles of patient selection and the indications for intervention during surveillance are reviewed in this article.

Active surveillance is an option for men with screen-detected, low-volume cancer. Patients with prostate cancer who fall into this category include men with a Gleason score of 6 or less, those with a prostate-specific antigen (PSA) value of 10 ng/ml or less and those with stage T1c or T2a disease. This definition encompasses about 45% of patients with newly diagnosed prostate cancer in a serially screened population. The concept is derived from the following five postulates: first, that screening for prostate cancer results in the detection of disease that in many patients is not clinically significant (i.e. if untreated, it would not pose a threat to health). Second, the patients who fall into this category can be identified with reasonable accuracy. Third, no treatment is minimal in terms of side effects and cost. Fourth, patients who are initially classified as low risk but who are reclassified over time as higher risk and treated radically are still cured in most cases. Finally, the psychological burden of living with untreated cancer has less impact on the quality of life than unnecessary, but curative, therapy.

Rational selection of patients for a surveillance strategy should be guided by these postulates. It is important to identify patients who have a low probability of disease progression during their lifetime according to clinical and pathologic features of the disease, patient age and comorbidity. Close monitoring of PSA levels and prostate pathology over time is essential. It is important that reasonable criteria for intervention are used, which will both identify patients with more-aggressive disease in a timely fashion and not result in excessive treatment, and to communicate appropriately with the patient, to reduce the psychological burden of living with untreated cancer